PARTNER OF NATURE

FOREWORD

IN his lifetime Luthur Burbank wrote or dictated many thousands of pages about his work with plants and the methods he employed in plant-breeding and improvement. Much of this material was published, but either in piecemeal articles that presented only phases of his work or his experiences or in sets of books that covered the whole field and offered more than the average reader required.

There were always requests for a single volume, written in non-technical language, that would cover the subject adequately — in short, for a compact and simple story of how Mr. Burbank went about his work of producing more useful plants, more desirable fruits and more beautiful flowers. Since Mr. Burbank's death in 1926 these requests have increased.

But it was a formidable task. There was so much material to sift and winnow in order to reduce the whole chronicle to so limited a space. It was my husband's own story, that must be told in his own words, yet what he had written had to be condensed into a smooth narrative.

However, the work was undertaken, under my supervision; it is here offered you, completed.

The experiences, theories, laws, methods and formulas set down are entirely Mr. Burbank's. The text closely follows what he wrote and dictated and said on the subject, though the "boiling down" process results in a transcription of Mr. Burbank's voluminous material rather than literal, word-for-word quotations. And, reading the manuscript, I am glad that this plan was followed, for Mr. Hall, who collaborated with Mr. Burbank during his lifetime, has a happy faculty for presenting him and his enthusiasms and adventures and work in almost the very words my husband would have used.

One of the sources for this transcription of my husband's writings was the eight-volume work, How Plants Are Trained to Work for Man, published in 1921 by P. F. Collier and Son Company, whose kind permission to refer to this work in preparing Partner of Nature is here gratefully acknowledged.

It is my hope that the work done on this volume will be justified by the interest it arouses, not only in Luther Burbank's experiences and methods, but in Luther Burbank as a naturalist-a true "Partner of Nature."

Elizabeth Waters Burbank
Santa Rosa, California

CONTENTS

A BIOGRAPHICAL SKETCH
The Life of Luther Burbank

LUTHER BURBANK was born March 7, 1849, the thirteenth child of Samuel Walton Burbank, whose forebears had been in New England since before 1640, and the third child of Samuel's third wife, Olive Ross, whose family traced its descent from the blood of Scottish kings. His birthplace — a large brick house with a wooden ell — stood on the sloping land that runs down from the old town of Lancaster, in Massachusetts, to the Nashua River. It was a house that threw its doors open hospitably to the learned, the cultured, and the scholarly who came that way or who lived — as many of them did — in the near vicinity. It was a house that heard many discussions of deep theological problems, of politics, of abstruse questions of philosophy and ethics; it was, moreover, the house of a successful and able father and a mother who was above even the high New England average of mentality and ability. It was a good house in which to be born.

There are many stories told of Luther Burbank's childhood that sound very much as though they had been suggested by his later career: the story, for instance, that as a mere baby his favorite plaything was a potted cactus plant; the story that he cried when flowers wilted or fell apart; the story that he instructed his mother how to plant and cultivate her garden when he was at an age when most youngsters are absorbed in teething. He himself tells of trying an experiment before he could walk, the experiment being the substitution of his chubby fist for doughnut dough in a kettle of boiling fat; he remembered in later life, too, that, while the rest of the family were picking strawberries one day and he was set in the field to amuse himself, he was delighted as well as alarmed by a big crow that tried to eat his pink toes. Whatever may the truth regarding his infantile interest in Nature it is unquestionable that his mind was bent and strongly influenced by the sober and thoughtful discussions he heard as he was growing up, and particularly and markedly by the long walks and talks he had with a cousin of his father's, Professor Levi Sumner Burbank, a personal friend of Louis Agassiz, a sound geologist, and a member of most of the learned societies that, at that time, were in existence in Boston.

It is agreed that he was a timid and sensitive child, which was partly traceable to the fact that he was of a delicate physique and so denied participation in the rougher sports of the other boys. But he was by no means diffident, nor soft; he played well the games he was strong enough for; he was a good skater; he was inventive and tireless in finding out the why of things; as he grew a little older he made himself liked and a sort of leader by figuring out short cuts in lesson-getting and acceptable excuses for having fun. Public recitation was his principal bugaboo, and "speaking a piece" utter misery for him. When he was entered at the Lancaster Academy, and by a sensible principal excused from declamation and permitted instead to write a composition, school lost most of its terrors for him and he became a successful student.

Meantime he had shown unmistakable aptitude for mechanics, experimenting with a tea-kettle until he made it operate a tin whistle; advancing from that stage to a cylinder-and-piston engine; perfecting that until it was practicable enough to run a small boat. He built water-wheels and set them to driving toys; he worked out labor-saving devices for his mother; he even planned a theoretical improvement on the process of brick-making, led to this by the fact that his father and uncle had turned their early pottery works into a brick-yard. His father began to think that Luther was wasting himself as a small and rather weak hand in the work of the home — the orchard, the timber-lot and the brick-yard; as there were plenty of older children who were rugged and capable, the youngster was at last apprenticed to the Ames Manufacturing Company with the belief that he would develop into a mechanical engineer and inventor. The guess was not far off, for the boy soon contrived a labor-saving device for the machine on which he was employed at turning plowrounds which multiplied the efficiency of both machine and operator many times over and which increased young Burbank's daily wage from a few cents to eight and ten dollars.

But the confinement and dust of the factory told on the fragile youth and, after his father's death, when he was about seventeen, he took the small patrimony that fell to him and, against the advice of family and friends, bought a seventeen-acre tract of fine land near Lunenburg, a few miles from Lancaster, and became a truck-gardener. It was the beginning of his real lifework.

Always groping about for an understanding of life and especially of the life of growing plants, Luther Burbank found his path brilliantly lighted by the first writings of Charles Darwin; what Darwin stated theoretically concerning the influence of environment on the heredity of all growing things the young gardener in Lunenburg began to demonstrate practically. His first experiments were simple; in fact they had probably been performed many times before. But he was different in this, that he began to formulate laws from his successful trials — to study the possibilities of that science which later brought him world renown and won him the first place in history for plant-breeding — the science of "training plants to work for man."

Out of many tests he made of the Darwinian theories and of the beliefs he himself was beginning to hold, two may be cited. In order to produce sweet corn for his customers ahead of all his competitors Luther Burbank set the seed to germinating in the house two weeks before the true coming of spring; this forced seed was planted, already germinated, on the day that other gardeners were sowing; two weeks before theirs was in the ear he was selling matured and succulent sweet corn throughout the countryside. He had proved that man's ingenuity could partially conquer the seasons. The second experiment he made was on the possibility of improving a common variety by selection. One day he found a potato seedball (a rare phenomenon, since potatoes have so long been grown from replantings of parts of the tubers themselves, and not from seed, that the potato plant has well-nigh ceased to bear fruit), and the twenty seeds contained he planted carefully. By shrewd selection, of which he was to become a supreme master, he eliminated the poorer potato plants that sprang from those seeds; when the little crop came to harvest he found that he had at least four vines producing potatoes considerably superior to any then on the market, and one so vastly better that it was practically a new vegetable. This was the origin of the Burbank potato — a product that statisticians once estimated added more than a billion dollars in fifty years to the wealth of the world.

All these early experiments in "training plants to work for man" had verified his expectations for them, in greater or lesser degree; the discovery of the improved Burbank potato gave him some cash; he decided to cut himself off from a family overconcerned to give him advice and from a climate and soil intractable and obstinate; in 1875 he removed to California and, that fall, settled in Santa Rosa, where he lived and worked until the day of his death. The satisfaction of all his obligations in Lunenburg had taken some of his capital, and for the first year or two he husbanded what was left to such an extent that he did some hard work for small pay and suffered some privations. But he was so fired with enthusiasm and so certain of the promise of his future that not even a severe fever which overtook him could conquer him and in 1877 he established himself as a nurseryman and began to finance his experiments (then kept strictly to himself) by propagating and selling nursery stock.

What Luther Burbank hoped to do with plants (to quote his own words) ran counter to all common experience. To think of changing the form and constitution of living things in a few years seemed grotesque even to many people who believed in the new doctrine of general evolution.

It was not generally admitted at that time that the plants under cultivation had been conspicuously modified by the efforts of man.

And even those exceptional botanists who believed that the cultivated plants owed their present form to man's efforts were prone to emphasize the fact that the plants had been for centuries under cultivation, and to question whether the modifications that could be effected in a single generation would have any practical significance.

So it seemed to most people who knew of my enterprise that it was a half-mad project and one that was foredoomed to failure.

Of course I had only enthusiasm, backed by the tentative results of early experiments in Massachusetts, to offer in response to such criticism. So it was necessary to trust to my own resources, and prove my case according to my own method.

In 1877 California was just beginning to show promise as a fruit-raising state; nurserymen who realized the possibilities at that early day required faith and patience but were rewarded presently by finding their wares in demand and their business respected. Luther Burbank, whose cards, letter-heads and advertisements announced him as "the Nurseryman south of the Iron Bridge" in Santa Rosa, took in $15.20 in 1877. In 1881, came the first opportunity to demonstrate some of his theories about training plants to accommodate and work for man; it marked the beginning of his career as a plant-breeder and experimenter, by proving that he was on the right track, by bringing him a substantial return in cash and by widely heralding him as an innovator and pioneer in a then almost undreamed field of activity.

A well-to-do business man and landowner of San Francisco, Mr. Warren Dutton, had become convinced that there was money to be made in the comparatively new dried-prune industry; he owned a suitable tract of land for growing the fruit; he wanted immediate results. Having heard vaguely of Luther Burbank he went to Santa Rosa in March, 1881, and asked the young horticulturist if it would be possible to furnish him twenty thousand prune trees ready for setting out that same fall. It was an unheard-of project, but Luther Burbank gave it a night's thought and decided that, if he were financed, he could deliver the trees. Dutton agreed to furnish the necessary money, and within two days Luther Burbank had secured and planted, in specially prepared beds, some 30,000 almond stones. Within a few days the almond sets were above ground and additional land rented into which to transplant them. The almond stock grew rapidly; in the latter part of June Luther Burbank obtained an ample supply of prune buds from a neighbor's fine orchard and for two months a force of expert men, under the close supervision of the young experimenter, was employed in placing the French prune buds on the almond seedling stocks. By the first of December, when Mr. Dutton was ready to plant his orchard, Luther Burbank was able to deliver to him 19,500 sturdy, budded, French prune trees.

Luther Burbank "botanizing" while on a vacation in the California mountains. Notice the concentration expressed in his half-closed eyes, which were said to be both "microscopic" and "telescopic" in their power; note also his fine, graceful hands — their power and sensitiveness — as he shakes the seeds from the pod of a wild red thistle.

The Dutton contract did all and more than was expected of it for Luther Burbank: it brought him in some much-needed capital, it gave him a statewide reputation that was almost sensational, and, of chief and most vital importance, it demonstrated to the plant-breeder and the horticultural world that, in one respect at least, plants could be definitely trained, directed, guided out of natural habits of growth and development, and made to serve man's urgent need somewhat at his will. Luther Burbank had from the first no doubts on this head, but it was something to prove the theory on a larger scale than ever before; it was more to make even a small part of the world acknowledge the point.

Gateway to Luther Burbank's Sebastopol Experiment Farm where most of his wholesale bulb, rose, and vegetable experiments were carried on, and all the larger fruit experiments.

Luther Burbank now bought a tract of four acres of land on the county road, west of his first location, and with the greatest care and at heavy expense began to prepare it for the work of his lifetime. Into the small cottage on the place he moved with his mother and sister, Emma, who had come out to join him; in that cottage he lived until 1906; on that four-acre-piece he performed most of the work with flowers and small plants that filled his life; under a Cedar of Lebanon which he planted there shortly after taking possession, he was buried when the end of his work came for him.

Luther Burbank's methods and technic in plant breeding and improvement, completely revealed in the pages that are to follow, and in his own words, were developing in his mind during the early years already sketched. Three have been outlined; that is —

1. Bringing about unseasonal growth (with the sweet corn at Lunenburg).
2. Taking advantage of the variations in seedlings (with the potato).
3. Speeding up natural processes in wholesale lots (with the Dutton prune order).

Other experiments that he had successfully concluded had demonstrated to him that the field of possibilities in plant breeding were almost limitless; he had proved by 1883 that he could (d) acclimatize plants brought from other climes and make them useful and valuable in America; (e) "domesticate" wild things; (f) by hybridization combine or emphasize characteristics in plants; and (g) by selection add desirable qualities to plants of all kinds already known and grown, obtaining, for example, new colors, larger flowers and fruits, more compact growth, improved flavor or fragrance, and so on. He knew that he was at the threshold of discoveries and achievements unrealized by any man who had gone before him; from that time forward he was never in any doubt, never hesitated, never could be discouraged nor turned aside. The story of his life from those years of the early eighties to the end was merely the story of how he put his new knowledge into effect for the betterment of horticulture and the greater happiness and good of mankind.

In the fall of 1884 he received a large consignment of Japanese seeds and seedlings, and the year following he sent for more, including several plums. He had already realized that, to get done what he wanted to do in the short span of a lifetime, he would have to perform all his experiments on a large scale; this required room and so he added to his experimental gardens a sixteen-acre farm, of land as fine as any in the whole state of California, at Sebastopol, eight miles from Santa Rosa, in what later developed into the famous Gold Ridge apple district. He now had room, as he put it, "to swing two cats in"; he began to communicate with plant and seed collectors all over the world and presently the mails were bringing him all he outside material he could use, and sometimes more, for his new work.

By inference the reader will find the story of Luther Burbank's life in the following pages, for his work was his life and his life was his work. His fame as a nurseryman was local, his fame as an experimenter and plant-breeder spread very slowly. In 1893 he published a catalogue, simple in appearance and modest in form, that set horticulturists, botanists and nurserymen by the ears and that, at first, brought him scorching condemnation for what the wiseacres said was his unthinkable effrontery. But presently it began to be known that what, in that catalogue, Luther Burbank had called "New Creations in Plant Life," were bona fide and that he could prove every claim. Slowly his name began to command respect; presently scientists and botanists, seedsmen and nurserymen, were beginning to make a path to his door; they were followed soon by reporters, journalists, photographers, the curious, the garden-lovers, the general public. Before the beginning of this century Luther Burbank had become "good newspaper copy"; in the year that Santa Rosa and California joined in celebrating elaborately his "Golden Anniversary" of achievement he was one of the ten best-known men on the whole earth, his plants and trees and flowers were growing in practically every corner of the land and myriad's of them abroad, and he had been loaded down with honors, degrees, acknowledgments and the friendship and admiration of men and women everywhere, great and humble.

Even more pleasing to him, though, was the love children bore him, for he loved them.

His marriage, in the sixty-seventh year of his life, to Elizabeth Waters, was to him the crowning happiness of his life; with faithful helpers in his gardens, and with his beloved dog, Bonita, half fox-terrier, half whippet, continually at his heels, he counted his blessings as complete. So his last years were filled, almost without a break, with contentment, peace and — to the very day of the beginning of his fatal illness, in March, 1926 — with the work he loved and at which he was tireless.

He was laid to rest under a Cedar of Lebanon in his gardens because he once said: "I should like to feel that my strength was going into the strength of a tree."

CHAPTER I
The Principles of Plant-Breeding

THE principles of plant-breeding are simple and may be stated in a few words. But to understand the why of those principles we who are interested in reasons and causes must begin with the facts of Nature that govern life-changes and improvements throughout the whole realm of biology and botany. If this chapter grows a little tedious, my recommendation is that you skip it; perhaps, later, you will want to come back to it when the more practical pages that follow stir your mind to questions and arouse your curiosity. But I will try to make even these dry statements as pungent and tasty as I can.

To begin with, every living thing is what it is as the result of the action of two forces: heredity, which is the sum of all the history and habits of the race, and environment, which means the numerous complicated outside forces continually working on the individuals of the race. The plant-breeder's work is to guide the action and interaction of these two forces — to take advantage of a plant's heredity and to influence its environment. And he is limited to these two means; there is no magic or wizardry in his business; he must work with the tools and according to the laws that Nature gives him, and his only improvement on her methods is to find short-cuts and invent devices for speeding up her processes.

When you look about you you see no development in the plants you know — they seem the same to you as they were when you were a child, and you wonder what is meant by "plant improvement." It is true that many varieties have experienced little change in the past few centuries — some of them little in the full breadth of man's history. Nevertheless we know that changes have occurred and are occurring; the very existence of the higher orders of plants was brought about by gradual evolution, step by step, from lower forms.

What is this "evolution" in plants? It is not so formidable as it may sound: it means that, through crossing — what in animals we call mating or breeding — variations came about; and these variations were such that a changing or new environment did not kill all the individuals, because some of them — those best fitted to survive — took root and grew and flowered and came to seed. And in the same way it means that there was a gradual improvement in the strength, adaptability and (as we shall later see) in the beauty and usefulness of the beneficent plant life on earth. At the same time and from the same cause there was an increase in the strength and viciousness of poisonous and destructive and harmful plants, for Nature plays no favorites and under her laws the gentle cow and the predatory wolf, the beautiful rose and the deadly aconite, the meadow-lark and the cruel "butcher-bird" have developed and become stronger through the generations. But on both good and bad sides weaklings and the unfit died.

All changes and improvements, whether good for man and animals, or bad for them, were made possible, I have said, through breeding or crossing. That is, through progressive developments in the heredity.

Close observation in your own garden or in any field or on any hillside will demonstrate to you that no two plants of any variety are exactly alike. Examine two heads of wheat, two violets, two pine trees, two apples, and you will find that each is an individual — as much so as people — even as much so as twins who, at a casual glance, appear identical. The plant-breeder, starting with this fact, searches for individuals having tendencies or powers or qualities that seem to him desirable, and by using them as "parents" presently finds himself with second or third generation individuals some of whom have those desirable tendencies or qualities slightly accentuated. It is thus that he makes his beginning toward the breeding-up of a new strain or variety. He also finds ways to speed-up this natural process of change, and because he can hurry Nature along he is able to do considerable in one lifetime — much more, you can see, than a horse-breeder can, for example, or a man who might be working with elephants.

Happily, Nature cooperates with the plant-breeder in his work, and when he understands the rules he can presently begin to use the second tool with which he begins — namely, environment. When we capture and domesticate plants and give them favorable surroundings — care, cultivation, water, protection from their enemies, and encouragement to put forth their best efforts — they have more leisure, so to speak — more surplus force — to comply with the demands we are making on them. There are plants that are obstinate and set in their ways; a little experience teaches us that these have always lived narrow, restricted lives — have been bound to a fixed environment, and therefore have had no experience in changing themselves. On the other hand all those that lend themselves easily to our efforts to change them are, we find, plants that have, through the ages, been in the habit of changing their environments — of adapting themselves to different climates, soils, and moisture conditions. You see, these latter plants have in them a heredity that has stored up life experiences under varying conditions, and therefore they will learn more readily, whereas the former kinds of plants — the one-type kind — have become set in their ways and don't know how to learn new ones.

Now, this ability to vary which is the plant-breeder's opportunity, arises from the fact of sex. There are living things that have. no sex and there are others that have the two sexes in one body; but those types tend to stand still, and have through the ages. Progress and change in nature, adaptability, and (for our purposes) beauty or usefulness to man are made possible through the fact that two individual plants, uniting, give their seeds all the powers and possibilities of both families, that may have come to maturity under considerably different conditions, even though they grew a few feet or a few rods apart. The mountain wolf comes down and mates with a plains wolf, and their pups are better fitted to live either in the mountains or in the plains than either parent was. So with the violet or the sunflower or the pine tree or the apple. This power to vary which results on cross-mating (what plant-breeders call cross-pollination, or hybridization), puts into the seed something invaluable to the work we are trying to do, because it enables us to select the individual plants that vary in a direction we want them to go.

The story of this influence of sex on all living things goes back to the earliest times, aeons ago, when protoplasmic forms multiplied by division — the breaking apart of cells. There came a time when some cells, we do not know why or when, developed specialized cells in themselves that had the job of reproduction given them; they were so simple in structure that they were dependent for transportation on water, and unless they were so carried they could not meet and mate with others of their kind. Naturally these primitive forms varied little.

Centuries passed and in long ages there appeared such plants as pines, depending for the mingling of their life-streams on winds. Now progress was more rapid, but it was still inconceivably slow until the next stage was reached — the stage when insects appeared. There followed an era of most astounding development. More than a hundred and forty thousand species of plants were brought into existence. At the same time a beginning of advertising was made — the use of beauty and color and fragrance and honey by the blossoms to attract insects so that they would not fail to do their job of transporting pollen and so mingling heredities. No plant or tree that depends on water or wind alone to carry heredity has bright colors, fragrance or a store of honey, while all that do have these allurements depend on insect life for hybridization. Later we will study the highly specialized appeals and devices that plants developed in this race to make useful friends of insects and birds; for the moment we merely observe that sex thus came into its full meaning and began to perform its real service in bringing together two different family heredities, merging them in one new-born individual, and so making possible the survival, through natural selection, of the fittest and best adapted and most adaptable "children" of a new generation.

It is plain that favorable conditions will enable any plant or animal or human being to reach its highest perfection as an individual; but the plant-breeder's task is not to concern himself with the individual as such; his task is to improve the whole variety. This job he begins with seed capable of variation; from the resultant plants he selects those that meet his demands; then, by repetition, he so impresses the improved characteristics on that variety that there is no slipping back into old inferiorities. You may observe in your own garden that, if you save seed from your sweet corn at random and plant that seed year after year, just as it comes, your sweet corn will deteriorate and become unsatisfactory and inferior in every way. But if you select your seed corn carefully you will get uniformly good quality. If, in addition, you weed out the inferior plants that result here and there even from the best of seed, you will get uniformly better results because you will be speeding up the action of improvement through natural selection. If, on top of this, you artificially cross-pollinate the very best plants and so accelerate the natural process of variation-toward-improvement, you will get the uniformly best results — you will, in short, be a plant-breeder. Finally, if you will persist, year after year, in this routine, you will fix the most desirable qualities in your corn and you may achieve what amounts to a new and improved variety. That, in substance, has been my work for sixty years. That is the formula for plant-breeding.

There are two questions all thoughtful people ask here, when they are thinking about the wonderful and beautiful machinery of evolution: first, why should Nature care what happens to a plant, or an animal or a man?; second, why does she care to improve the race, or any species? The answers give you a still clearer view of the wonderful scheme of things.

First: Nature cares little or nothing for the individual, but she jealously and continuously guards the species — the whole community of individuals — against extinction, and erects about it amazing and complex protective defenses to secure its perpetuation. To be sure she can only work through the individual, but her purpose is to equip that individual so that, if it lives and matures, it will be able, not only to reproduce itself, but to mingle its life-stream with that of another individual to give the next generation even a better chance than the parents had. You will read a lot about this subject later on in these pages; here it is only necessary to cite one example of Nature's indifference to the single plant as such, and her infinite care of the species. The example is the mustard that produces thousands of seeds and scatters them far and wide, even though it is certain most of them will never germinate or, if they do, will die; yet some few of the tiny black particles will certainly find root and life.

Second: Nature does not seem to be interested in the improvement of the plant or animal — her preoccupation is in making it ever more and more fit to survive in the universal struggle for existence. For man's purposes it may not be the "best" that live but it will certainly be the most fit — that is, the strongest, the most adaptable, the hardiest. Weaklings, the malformed, the unfit, are crowded out or pushed aside or destroyed by enemies, in the natural state. Civilized human beings are the only animals that seek to preserve their unfit and (what is worse) permit them to reproduce their kind. Everywhere else in her wide domain Nature eliminates them.

The natural process, therefore, is keyed all along the line to the preservation and reproduction of the individuals most fit to survive. These not only live but they thrive, for they are strong enough to seize the best food, the most favored environment, the safest spots for growth and for their descendants. And this is not a static process, but is a forward-marching process. Not only must the strongest and best individuals survive and thrive, but constantly changing conditions around them require that they reproduce themselves (through the mingling of strains by means of sex) in sturdier and stronger and more adaptable forms.

It would be easy to say that this process is one of improvement and therefore that betterment must be Nature's aim if it were not for the fact that, when Man speaks of improvement, he means betterment from his point of view — an improved condition to meet his needs or demands. There is a great deal of that sort of improvement in Nature, as when the pines and oaks grow strong enough and sturdy enough to withstand the fiercest storms and therefore to furnish Man protection from them. But you would not say that it was an "improvement" as far as you are concerned that the blackberry vine has, in past ages, learned to protect its seed-bearing berries by putting out a myriad of thorns! Nor that the tumbleweed is "improved" by becoming light as a feather when dry, and shaped like a ball, so that the wind can roll it across your field and scatter its vicious seed hither and yon to infest your wheat! No, Nature wants to protect the species from destruction and make it certain that it will reproduce itself-and there she stops. But under her laws it is Man's privilege and opportunity to take advantage of the plant's adaptability; to step in and actually improve her children for his own use and better them from his own point of view! And that, of course, is where the plant-breeder enters the picture!

This seems as good a place as any for me to say that the possibilities of plant improvement are infinite and that the surface has only been scratched. If the potato could be improved so that its value to the human family was increased in fifty years more than a billion dollars; if new fruits could be developed by one man during the course of his lifetime, while tens of thousands of experiments in other lines were continuously going forward, so that the whole history of orchards and fruit production was affected favorably; if hundreds of new plants and flowers could be introduced to brighten gardens and to increase the income of the truck gardener, while all the other work was progressing, then it must be obvious that the task is not finished. It is, in fact, barely begun.

The inventor, the chemist, the electrical genius have all contributed untold wealth and happiness to the world, and their work still goes forward. But I assert that the most priceless legacy which man has ever received from any source in the study of Nature lies in learning to guide the creative forces of plant life into new and useful channels. The possibilities are little understood, and can scarcely be estimated. It would not be difficult for one man to breed a new grain which would produce one grain more to each head, one more apple, plum, orange or nut to each tree, or one more potato to each hill.

What would be the result? In five staples only, in the United States alone, the inexhaustible forces of Nature would produce annually, without effort or extra cost, 6,000,000 extra bushels of corn, 15,300,000 extra bushels of wheat, 42,000,000 extra bushels of oats, 2,100,000 extra bushels of barley, 24,000,000 extra bushels of potatoes. If it is objected that we are now producing more than we should (which seems sometimes true, even though in fact it is not), let us change the hypothesis and suppose that the plant-breeder produces the same amount of grains and vegetables and flowers and fruit, but makes them richer, more succulent, more valuable to eat, or more gratifying to see and smell. Let him give us quality, rather than quantity, since he can do either, almost to your order. Would that not be of inestimable value to mankind?

And these vast possibilities are not alone for one year or for our own time or race, but are beneficent legacies for every man, woman and child that shall ever inhabit the earth. Moreover, who can estimate the elevating and refining influences and the moral value of improved flowers, with all their graceful forms and bewitching shades and combinations of colors and exquisitely varied perfumes? These silent influences are unconsciously felt even by those who do not appreciate them consciously, and thus with better and still better fruits, nuts, grains and flowers will the earth be transformed and our thoughts turned from base, destructive forces to nobler productive ones which will lift us to higher planes of action. On that happy day man shall offer his brother man, not bullets and bayonets, but richer treasures of the earth!

CHAPTER II
The Romance of Struggle

EVERY native plant growing on any desert is either bitter, poisonous, or protected by spines or thorns.

The sagebrush has a bitterness almost as irritating as the sting of a bee; the euphorbia is as poisonous as a snake; the cactus is armored like a porcupine not only with large spines that would frighten off the bravest but usually with microscopic needles that form a secondary and very adequate defense. Why? For the same reason that bees have stings, that snakes have fangs, that porcupines have quills — for self-protection.

Self-preservation comes before self-sacrifice in plant life as in most other living forms. Now if the bitterness, the poison, and the spines of these desert growths are there as a protection then they must have been acquired as the result of some urgent and compelling necessity, for there was a time when they were not needed, as we shall presently see. Here let me say that this is not a theory with me; it is a fact which I have proven again and again, and definitely with the cactus itself. For on my farms the cactus, given my protection and that of my fences and my helpers and my good soil and my planned care, has come to grow without those protective spines and to produce incredible amounts of excellent forage and of delicious fruits. And if the plant had not at some time been unprotected it could not have been induced wholly to abandon the habit of growing its armor.

"But," you say, "granting all that, do you mean that the cactus at some time in the past foresaw the coming of an enemy that threatened its existence? Is it possible that a plant, like a nation expecting war, could arm itself in advance?"

Let us look for our answers into the history of the cactus.

Those parts of California, Nevada, Arizona, Utah, and northern Mexico, that are now the home of most of our cactus, were once the bed of a sea. All around that inland sea grew perhaps a myriad of plants, of many varieties, thriving and multiplying in the climate made pleasant by the great body of water there. Among these was the cactus, undoubtedly with well-defined stalks, thin leaves, succulence, and more or less inviting fruits.

But physical changes in the region resulted in cutting off the sea; heat increased; the sea dried up and disappeared. In its place developed a wilderness of sand — a formidable desert. Here was a challenge to all living things in the region; animal life could flee before the increasing heat and aridity, but the plant life was doomed to stay. It must either adapt itself to new conditions or perish. And the cactus began the adaptive process at once.

It gradually dropped its leaves in order to prevent too rapid transpiration of the precious moisture. It sent its roots deeper and deeper into the damp substratum which the heat of the sun had not yet reached. It thickened its stalks into broad slabs. Thousands of individuals died, but the species persisted. At the same time there were probably other families of plants that failed to transform themselves rapidly enough and that perished. The sage and the cactus, the mesquite and the arrow-weed — a few lived, only because they were able to keep step with environmental changes.

But now we find another enemy entering into the life-story of the cactus: hungry animals, perhaps antelope. They fell on the succulent and moisture-laden plants (the cactus is, by weight, more than 90 per cent water!) and soon were threatening the desert growths with extinction. Therefore those that were to live must add to their heredities another protective device — armor without, or distasteful or dangerous elements within. Undoubtedly the cactus family lost millions of members here again, but a few thousand lived, because they chanced to have a tougher fiber and outer skin and because they had rudimentary spines. The few, even though eaten to the ground, were strong enough to send up new leaves, and with each new crop the "hairs" on the leaves became stiffer and longer, harder and more pointed, until finally, even if there was only one survivor, there was developed a cactus effectually armored against its every animal enemy.

Now observe that this severe testing and this desperate struggle, just as test and struggle give us humans greater strength and capacity, endowed the cactus with many truly remarkable powers and qualities, some of them almost unique in all horticulture. The cactus slab has in it a life-force that is incredible for strength and vitality. Lay one of them on hard ground, without water, and presently the "eyes" on the underside will begin throwing out roots. If they get the slightest foothold the "eyes" on the upper side will develop baby slabs and blossoms. Young cactus slabs that I laid on a burlap-covered trestle of boards threw out long roots in a few days that grew until they reached the ground, three feet below. A cactus plant pulled from the soil and tied in a tree remained there for six years and eight months, and at the end of that time was planted and grew. A slab, long forgotten in a closet in the dark, was found after two years — and on it was a puny, sickly, but living baby slab!

There is the answer of Nature to your question. The cactus did not "foresee" the vicissitudes and arm itself against them, but Nature had stored in the plant, as she does in all living things, the power to vary and, when environment changed, those variations were wide enough so that the whole life-story of the cactus was changed.

ABOVE: An early stage of the great spineless-cactus experiment. It was carried on for twenty-five years, ended in the complete achievement of the naturalist's purpose.
BELOW: Close-up of spineless cactus. When perfected, it produced prodigious tonnages of smooth, succulent leaves, useful for feeding stock and entirely free from spines. Prejudice and neglect to follow his hints prevented the Burbank cactus from coming into wide use.

This power in any species of plants to vary is illustrated in another way by the algae. In one form, or branch, it exists as the snow plant, a beautiful red-flowering spike that grows in the ice and snow of Arctic regions without touching earth; another division of the same family grows in the waters of Arrowhead Hot Springs, in southern California, where the temperature is so high that eggs may be cooked in the self-same springs. Another cousin is the mighty growth of the Sargasso Sea, made up of small algae plants growing in dense and tangled masses; some algae grow on and in animals, some on other plants, some on iron, some on dry rocks, some in fresh water, as in garden pools.

Another example of variation, remarkable because the divergent types are but a few rods apart, is found in a member of the lily family — the trillium — in mountain canyons in California. The flowers of the plants growing on the shady side of the canyons are larger, the plant leaves broader, the bulbs smaller and nearer the surface; on the other side of the canyon, where the trillium is exposed to the sun, the bulbs are larger and grow deeper in the soil, and the leaves and blossoms are smaller, to conserve moisture.

But I think the most sensational adaptation I have ever encountered is that which, in past ages, has been made by certain pines in parts of California where the presence of volcanoes must once have caused frequent and destructive fires. The cones of most pines take two years in which to mature the seed, therefore those cones open at the end of that period to release the precious germs for growth. But if these seeds do not germinate at once thereafter, they die. On the other hand the pines I am writing of in the volcanic sections of the Southwest produce cones in great abundance and at a very early age, some of them when the trees are only two or three years old. These cones remain closed on the trees so persistently that the new wood sometimes grows over them, but the seeds inside remain strong and alive. And here is the marvelous fact about these fire-challenged pine cones: the cones refuse to open until a fire has swept over the region; then the accumulated supply of cones open, even though thirty or forty years have elapsed, and the next year the ground all about will be found covered with baby pinelets almost as thickly sown as grass seed in a lawn. Of course, very few of these survive, due to the crowding, but the strongest of them persist and so, even after a destructive fire, those amazing pines spring into being again and, though individuals have been lost by the millions, the species persists!

Now let us consider another phase of the struggle for existence and its romance in the plant world: the infinite ingenuity of variations in Nature.

Did you ever stop to wonder where flowers get their colors? They have them as a response to the color senses of bees, butterflies and birds; they acquired them through ages of adaptation in order to attract the insects and birds that were useful to them in effecting cross-pollination.

Let us pick up a carnation or any other common garden pink (Dianthus), and examine the structure. If we strip off the petals soon after they have opened from the bud and slice the blossom in half we will find ourselves looking into a tiny, long, cylindrical nest of dianthus eggs — soft, white, moist, mushy eggs with only a tender, skinlike covering as shells. Neatly packed in a pulpy formation these eggs are incased in a well-protected nest, longer than its breadth and oval except that its top extends upwards in the form of a single tiny stalk. Surrounding this bag of eggs with its single upright stalk, and hugging it closely all around, are very slender, modified leaves, half an inch in length, each ending in a pointed spine about the size of the bristle from a hair-brush, arranged in circular form to shield the egg chamber and its central stalk from harm. At the top of the surrounding stalks we see crosswise bundles, neatly arranged, of beautiful slate-gray pollen dust, loosely held in half-burst packages. At their base we find the dianthus honey factory and the fragrance shopa group of tiny glands which manufacture a sticky confection that covers the bottom of the flower with sweetness and delightful odor.

Shall we take one of those egglike seeds from the nest and plant it? We might as well plant a toothpick! Shall we take a package of the pollen out and plant that? We might as well plant a pinch of flour!

Four seedling roses which were tested by being planted along the porch of Mr. Burbank's Santa Rosa home. They were all of the "cluster" type, most of them fragrant, all of them popular and widely planted after the introduction of the best of them by Mr. Burbank or by nurserymen who bought from him.

But let Nature combine a grain of that pollen with one of those eggs into a seed and in ten days in the soil it will develop into a living, growing thing — a new dianthus plant, with an individuality, a personality all its own; something that has never lived before, yet that has within it all the tendencies inherited from ages of ancestry, waiting only on environment to determine which of those inherited tendencies shall predominate. We all know enough to be satisfied that we could not ourselves cover the ripened seed with the pollen and get results, but we can work with Nature — become plant-breeders to that extent — and by this cooperation achieve results. How do we go about it?

Examining the central stalk that grows up from the nest of eggs we see that, as the flower grows older, the stamens fall away and a transformation occurs in that stalk. Its upper end, which at first was single, now shows a tendency to divide into two or three curling tendrils, moist and sticky, and covered with hundreds of microscopic fingers designed to catch and hold pollen dust. Our share of the task of cross-pollination is to take a few grains of pollen, place it on one of these stigmas as they curl from that central stalk, which is the pistil, and so start an immediate and vital process in motion.

Once planted on the stigma of the pistil the pollen grain begins to throw out a "root" downward through the stalk of the pistil until it taps the egg chamber and makes possible a union between the nucleus of that pollen grain and the egg below. The crossing or "breeding" of the dianthus is thus finished and it remains only for time to develop the seed in its tight little shell until, ripened and dry, it is ready to be planted and to furnish us with that new dianthus individual we have mentioned.

But here is the marvelous and ingenious difficulty made by Nature to insure cross-pollination in the pink: the ripe pollen dust is always gone in the flower before the pistil opens its sticky fingers to receive it. Therefore, to make a combination between pollen grains and the egglike seeds it is necessary to find a blossom that is in its pollen-bearing stage and then find another blossom which has passed this stage and shows a receptive stigma. We are compelled to make the combination between the two instead of in the one blossom. I have already told you that Nature insists on preserving the species; we may now add the law that she usually insists on cross-breeding to insure variation, which insures a commingling of inherited tendencies, which insures the power of adaptation to a changing environment. And now perhaps you begin to see what a field the plant-breeder has open before him! Taking advantage of this law of Nature he can produce, almost at will, new colors, new odors, new sizes, new plant-forms — even new varieties, and therefore an absolutely infinite number of combinations of these.

But we must not lose sight of the part that insects play in the normal development of Nature's scheme — the reason for color and perfume and honey in the flower. The dianthus, or common "pink" is a good object lesson, because it is one of the many flowers that have been so anxious to produce variations in the offspring that they have lost the power of self-fertilization, risking their whole futures upon the cooperation of insects and other means for bringing pollen from a neighboring plant! And that would be too great a risk for Nature to permit the pink to take if the flower had not clothed itself in beauty to attract the eye of insect and bird, developed a perfume to appeal to the sense of smell and baited its friendly trap with honey to induce the pollen-bearers to come inside where they would be sure to catch on wings and legs and bodies some of the precious grains.

Now compare the romantic struggles for existence of the cactus and the garden pink! The cactus had to arm itself, provide itself with ample water in an arid land, don a thick, crusty coat to prevent evaporation and develop amazing vitality so that it could lie neglected for years and then, when the opportunity was afforded, burst into abundant life again. The garden pink had no such problem, but it was seeking variation in its children, so it went to all the trouble of dressing itself up and perfuming itself and adding a candy-factory to its equipment, to invite bees and insects of all kinds to come and do for it the pollination work it could not do itself unless it were to inbreed over and over again and so degenerate or be snuffed out by an unfriendly environment. And it is worth while to note here that the reason the dianthus, among many flowers common to most of the gardens of the world, is found everywhere is that this habit of cross-pollination, giving it the power to vary, has made it able to grow in almost any soil, in almost any climate, and under almost any condition of cultivation that you choose to name!

Another example of the romance of the struggle for existence in flowers is furnished in remarkable fashion by the arum (A. dracunculus ) that is sometimes called the carrion lily. This is of a color and texture like liver or an "overripe" beefsteak, and it gives off a most penetrating and distasteful odor very like that of spoiled meat. As there is a reason for everything in Nature, if we search far enough, so there is a reason for the ugliness and stench of the carrion lily. What is it?

Undoubtedly this arum, stranded sometime in the past in a place where flies were its only available messengers of reproduction, was compelled to make itself attractive to those flies. Now, flies prefer carrion to anything else, so the stranded flower gradually adapted itself to this fact and both in appearance and, in odor suggested to the insect that here was his favorite dish. And to make doubly sure that any visitor would receive its load of pollen the carrion lily developed so that it can close on the entrance of the insect and hold him there for a time, while he beats his wings and buzzes about angrily, seeking to escape. Slowly, then, the flower unfolds and the pollen-laden fly wings away, to find another carrion lily presently and, in crawling in through the narrow throat of the flower, dust off against the stigmas the precious pollen.

In order to vary so that the species may be certain to survive (this is the refrain this chapter sings for you!), let me quickly give you four out of the thousands of interesting tricks of flowers to insure pollination.

In certain varieties of sage the pollen-bearing stamens actually descend and quickly rub their yellow dust on either side of the entering insect, after which they fall back into their proper position.

Some orchids bear their pollen in small, compact bundles so placed that no visitor can come and go without having one of these bundles attach itself to his head. It glues itself there and curves upward almost like a horn. But once the insect is free the horn bends downward so that when entrance is made to another orchid there is almost no possibility of the pollen bundle failing to reach the pistil of the flower. There is another orchid that goes farther: as there are two stigmas it loads the caller down with two bundles so nicely placed that they will almost certainly touch both the proper receiving stations in the next flower visited!

The pollen of the milkweed is stored in two tiny bags connected by a sort of strap; in the strap the feet of bee or honey-loving beetle become entangled and so that delivery is guaranteed!

But we cannot linger longer with this fascinating story. We must get on, for Nature has many stories yet to tell us, and after that we have to come to the main job, which is to explain how all these devices, rules, tricks, subterfuges, and processes are used by the plant-breeder in "training plants to work for man."

CHAPTER III
The Rivalry of Plants

YOU have observed perhaps that the economists and other wise fellows who tell us about business, finance, commerce, and those complicated subjects, talk a great deal about this "age of competition" in which we live, and you might almost think that cut-throat competition was something man had taken out a recent patent on! But it is not true: for ages animals and plants have been competing — have been rivals in business, just as our merchants and manufacturers and shipping men are to-day, and the competition has been for the same purpose — a race for prosperity — that is, for "a place in the sun."

We have seen that flowers donned beautiful colored dresses and put up confections and gave themselves odors to attract the insects; but there are certain plants to which color is a disadvantage — for instance, the night-blooming flowers. At night a red or blue flower would not be seen, therefore you will find that the flowers that blossom at night only — and there are many of them — are invariably, as far as I know, either white or yellow. Why? Obviously, so that they can be seen by night-flying insects.

The fact is that the advertising business, which has grown so great because of the keen competition between men to sell their wares, is an old art with the plant world: color and odor and nectar are all advertising devices. And we find certain flowers that carry the advertising campaign to pretty great lengths, some of them with variegated gowns planned to please every taste; some set on stems so fragile that they dance with every slight breeze, thus calling attention to themselves with movement as well as color and fragrance; some have a pretty trick of pretending to hide, thus exciting the curiosity of and inviting visits from alert and inquisitive insects, which are the very kind best suited to do the work of pollination for the shy blossoms.

Let us look for a minute at the corn. Corn is a businesslike and efficient vegetable, with no time for foolishness and no taste for colors, therefore it must have long since given up hope of flirting with the insects and have decided to trust to the wind, which has always been a good friend of plants and trees. And so the corn grows tall and supple, holding its pollen-laden tassels at the top where the wind, swaying the plant, can shake loose the pollen grains that fall toward the ground and are caught on the way by the silk rippling from the growing ear. Trace each thread of silk back and you will find it ends in a kernel of corn. The corn silk is to the corn what the pistil is to the flower — a through-track to the seed that lies there waiting to be fertilized. And as corn depends on the wind, so do many other grains; so do pines; so do our grasses.

We have seen that the cactus was a stay-at-home body; let us look now at an inveterate traveler that has spread over many countries, thousands of miles apart — the cocoanut palm. In fact it grows in so many places, in the hotter climes of the world, that no one has yet decided just where it originally started from. The cocoanut palm is in business in a large way, and its zeal to claim new territories led to a clever and interesting development of its nut. The nut itself grows and comes to maturity encased in a tough, fibrous covering that clings tenaciously to it for a long time after the nut falls. As the palms grow along water courses and the sea the ripened fruit often falls into water; presently, even in salt water, one of the three eyes at the end of the cocoanut softens and from it grows a tiny rootlet that winds and winds itself about the nut itself but inside that outer coat of fiber. When the nut is washed ashore, perhaps hundreds of miles from its first home, the roots are so well developed inside the fibrous coat that they can catch hold at once in any bit of soil they find, and soon from another eye, or perhaps from two, a baby palm shoot appears and the cocoanut is established and sets up in trade for itself!

A tough little wanderer is the dandelion; it may be that there was a time when he became tired of growing in a limited locality and decided to go out and see the world. And his seeds are now well equipped for journeying, for each is attached to a lighter-than-air fairy balloon with sails — and how they go, up and down, here and there, far and wide, to settle at last in some distant spot! Millions of them fall on rocks, hard ground, the sea, perhaps, but there are so many of them that enough always catch root to make the dandelion a pest to home-folks, especially in lawns. And the dandelion is only one of a great variety of flowers with balloons or aeroplanes or sailboats to carry their seeds about!

One of the wild chicories, in this race to secure business, has even gone so far as to raise two kinds of seeds — those equipped to fly and those that are wingless. The first spread the chicory plant abroad; the second stay at home and keep house somewhere near the old folks; there is no danger of that chicory family dying out for a long long time with such a double provision made!

When I was a boy we used to get a lot of fun out of what we called "the squirting cucumber" which, when ripe, can shoot its seeds with such force that they are carried as far as twelve or fifteen feet away. Another device to insure the perpetuation of the species!

Most of the plants whose seeds grow in pods have, because of that, the power to cover considerable area with their seeds: when the pod ripens and becomes brittle and dry a slight touch or the heat of the sun will cause it to explode and scatter the precious seeds. In Mexico what is called "the jumping bean" has formed a strange sort of business partnership with a moth that, when the pods are green, lays an egg in each one. As the pods ripen the moth egg hatches and the larva begins to feed on the pulpy inside lining, but without harming the seed. The pod shrivels and curls as the larva hollows it out and as the season dries it up; now when the larva moves about it causes the pod to roll and jump in a fashion that is excessively funny to watch but that has, in Nature's system, a definite purpose — it gives the pod locomotion and so brings it to a new location where it can be pretty sure to find a crack or cranny in which to grow.

The "devil's-claw" (Martynia ) has developed a power to bite and cling with cruel ferocity to any passing animal; it hooks its claws into leg or side and then, when the tortured animal runs or tries to scratch it off, the pod drops its seeds, one by one.

These are just a few of the ways in which plants, in the keen competition for growing space, for advantage in the struggle, for dissemination of their seeds to insure variation and so insure themselves power to adapt themselves to changing environment, compete with their brothers. Wherever we look we see some new display of ingenuity, and it is all, finally, for the sake of variation, which may mean retrogression in some cases but which, in the long view, means progress. Every flower that delights our eye, every fruit that pleases our palate, every plant that yields us a useful substance, is delightful or pleasing or useful simply because of the improvement that has been made possible through variation.

In every plant that grows we see two tendencies — one to ward off enemies, the other to make use of friends.

To plants growing wild, frosts, winds, storms, droughts and vegetarian insects and animals are their principal enemies. In the wild state, again, bees, birds, and butterflies, the warmth of the sun, the moisture and fertility of the soil — these are their principal friends.

But when we transplant these growing things and put them under cultivation, we upset their whole environment.

When we build fences around the blackberry we remove its need for thorns. We save the seeds of the radish and the bulbs of the lily, and with our human organization distribute them and plant them wherever they will grow. We cut grafts from our apple trees and ship them the world around. We select and improve, we cultivate and tend, we water and protect all seedlings and give them every favoring condition possible; we remove what for ages have been the chief problems of their lives — we take over their two principal functions — self-protection and reproduction. And presently these favored plants begin to grow more and more for man, catering to his wants, advertising to him their strong points, and working for him to the best of their several abilities.

Here is an example of precisely what I mean.

The common "snowball" in its wild state wears a mere fringe of blossoms around a thickly populated community of egg-nests and pollen; it is advertising to the bee with those flowers, because it needs the bee in its business. But the snowball in my yard, the child of many generations grown from cuttings and carefully nurtured, knows no need for stamens and pistils and has therefore turned them into petals and its eggs are sterile. Cultivation, in brief, has relieved it of the necessity for reproduction and what was once a fringe of flowers has become a solid mass.

Another example is the violet that, in its early history, had a bitter struggle for existence because it grew so close to the ground and must have been more often crowded and perhaps killed by other plants than enabled to mature. There are violets that put out advertising blossoms at the top of the plant, inviting bees to help pollinate them, and at the same time grow small, dull-colored, closed blossoms near the ground that, because the bees cannot even find them, have gained the power to self-pollinate. Other violets produce only the advertising flowers, having got their flowers up off the ground and therefore having no further need of those low-growing basement egg-nests.

Into the life of one of the violets a few hundred years ago man came and the flower found itself tended, cultivated, properly watered and encouraged to thrive. Soon this particular violet, as if assured of reproduction, abandoned all its strenuous efforts and devoted itself, in gratitude and confidence, to making bigger and more beautiful and more variegated blossoms for the creature who had been so kind to it — and there you have the life-story of the violet which we now call the pansy!

For a moment let us turn to a common fruit for one further illustration of how plants change their whole life histories to please and gratify man. On my experiment farm at Sebastopol grow two ordinary looking pear trees: one of these produces delicious pears, a delight to eye and palate; the other yields pears that are juicy but that never become mellow and that in their uncooked form are almost indigestible. The trees look much alike; it is only in their fruits that they differ.

To understand this difference we must go back to the beginning of the story of the pear. It originated in Eurasia, and gradually spread or was carried by man east and west, north and south, so that there is probably no variety of fruit now more widely propagated. The pear tree on my farm that bears the luscious fruit is a Bartlett, the child of pears that moved steadily westward from its Eurasian native land, going to Europe, to England, across to North America in the early days and so gradually westward to California. The pear tree next it that bears the hard and unpalatable fruit is one I imported from China — the child of pears that worked slowly eastward from the Eurasian land of its origin.

Why are they so different? Simply because the American prefers his pears large, sweet, juicy, aromatic, and delicious in the raw state as well as when cooked; in Japan and China they do not understand this notion of eating pears raw — they must have theirs hard but juicy and suitable for pickling, preserving or making into a sort of candy, like our glace fruits. Neither of the two pears is anything like its Eurasian ancestor: each has changed, in the centuries, one toward one set of ideals, one toward another. The pear had the difficult and constant struggle for existence that all other plants have had; it depended for its variability on crossing; it changed and developed and grew sturdy and able to take care of itself in arid land (the pear even now can not stand too much moisture — underground moisture that is too plentiful will kill it every time!) — then, at last, man entered on its scene. In Europe and later in America we informed the tree that we liked fruit that was ready to eat; we refused to have anything to do with it unless it could furnish us that sort of product; gradually we weeded out all those pear variations that did not meet our taste, so that at last we have practically nothing else from it. In the Orient they taught the pear tree that they must have fruit that was juicy and flavorsome, but not soft nor sweet nor mellow when ripe; in time the pear quit trying to foist on the Oriental gardener a fruit that was anything but exactly and specifically what he desired.

Man is the most important influence in the life-history of plants; by this I do not mean those few of us who have devoted our lives to their training and development, but man in the mass — and not only modern man, busy with his store or shop or mine or mill, occupied with his law or his finance or his medicine, but all mankind, back to the primitive. Perhaps even prehistoric man (and woman) scratched at the ground to help their plants grow. Certainly the earliest records we have of the race show that he dug the soil, planted, watered, harvested.

For instance, it was the Indian who gave us the most important crop America produces — corn.

On one of my experiment farms I have grown the original variety of corn which the Indians found and improved until it became the staff of life for two continents — South and North America. The Mexican Indians called it teosinte. It bears tiny ears with two steel-armored rows of barleylike kernels on a central rachis, or spine, not as large or as strong as the central stalk of a head of wheat.

When those ignorant savages discovered, either by chance or by study, that the few grains borne by the teosinte were palatable and nourishing they began to make crude garden beds, plant the seed with care, perhaps carry it a gourdful of water in the hottest weather of the spring and certainly to give it the best chance they knew how so that it might develop and not be choked out by weeds or burned up by the sun's heat. The teosinte responded. Since it had in its life-germs the power to vary it inevitably varied in some cases in the direction of sturdier stalks, or larger ears, or more numerous rows of kernels, or with kernels themselves of greater size. Or, in rare cases, perhaps in more than one of these particulars.

From two the rows of kernels increased to four — to eight — to twelve and more. Slowly the corn plant itself changed; the larger and sturdier it became the greater necessity it found for changes in root structure, so this developed and spread out to support the taller and more luxuriant growth above; the tiny ear became a sizable affair; the kernels grew to many times their original size. The Spanish called it "maiz" and carried it north into the regions that are now California, Arizona, New Mexico; the use of it spread rapidly. Originating in a hot climate it found itself slowly moved into areas colder and colder, so that it was forced to change its growth-habits — come to maturity faster, for example, and germinate in the chillier mornings of the northern summertime. It had to adapt itself, in short; it was able to do so because it had the power to vary and because it had the friendly — though selfish — assistance of man.

Oddly enough it has not been only an increased usefulness, sturdier growth, or more generous production of fruit or grain or blossom that has resulted on man's interest in plants. Even his eccentricities of taste and other characteristics have been impressed on his growing things. Let me tell you a story that illustrates that angle.

Peter Barr, a great English bulb expert, once bought the entire daffodil gardens of two of his countrymen who were persons of an almost directly opposite build, nature and taste, one from the other. In some way the two collections became mixed, so the bulbs were planted indiscriminately. Yet, when they came to blossom, Mr. Barr could tell you without hesitation which daffodil originated in the collection of Mr. A and which in that of Mr. B. When I asked him how this was possible he explained that Mr. A was a large, florid, ostentatious man; B was quiet, cultured and had fine taste and great discrimination. A's daffodils were like himself — showy, brilliant, big; Mr. B's were delicate, dainty, charming. A had only grown and bred the kind he liked — unconsciously, perhaps, he had liked the flowers that resembled himself. The same for Mr. B.

I have often said that your garden tells a story of yourself and your nature and character that any discerning man can read. It is, in fact, a sort of photograph, in pattern and color, of your disposition, habits of mind, tastes, and likes and dislikes. To that extent have flowers varied to please and gratify man; to that amazing extent have they developed, and will continue to, to meet his wishes!

CHAPTER IV
New Flowers and New Colors

AMONG our human acquaintances we know those who are sturdy and those who are weak; those who have well-developed minds at the expense of their muscles and those with well-developed muscles at the expense of their minds. We know some who are tall and some who are short; some with brown eyes and some with blue; some who lean toward commerce and some who lean toward art; and so on and on and on through an infinite number of variations and an infinite combination of these variations, each variation representing the result of present environment reacting upon all the environments of the ages, stored in us at birth — that is, upon heredity.

Let us observe one of the enormous advantages to the race of these varying characteristics and temperaments in people. As a means of locomotion we had our feet, first; then we rode horses, made crude carts, improved them and made carriages and wagons and stages; then, suddenly, the railroad came. On the day the first successful engine and passenger car moved along fixed rails there were not more than three or four men who knew anything about railroading in any of its branches.

And yet, in a generation, we found variation and adaptability enough among us to develop surveyors to carry their transits over the plains, rivers, mountains, and lay out a route; draftsmen to put the plans on paper; we found woodchoppers to make ties, bridge-builders to erect stout bridges across the streams, steel-makers who for the first time in their lives designed and modeled and made steel rails; we found engineers and firemen and switchmen; we found superintendents and presidents; we found every man we needed to make this unheard-of experiment a complete and permanent success as the world's primary means of land transportation. The variation of characteristics, temperaments, abilities was there in the race, and when the need arose the individuals peculiarly adapted to the purpose were at hand, thanks to variability, to perform the function.

Sometimes people marvel that a heterogeneous group of colonists could think out, frame, set up, and put into working order a new government in America in 1770-90; but there is nothing strange or marvelous about that fact except as the laws of Nature are strange and marvelous and amazingly exact. For, when you examine the facts, you discover that the great majority of the people who made up those early American settlements were people who had rebelled at the old forms of government, whether in England, Scotland, Ireland, France, or the Palatinate of Germany; they were dissatisfied with the conditions of their lives, principally because they had been persecuted for the sake of their several religions; they were bold, desperate, and resourceful men, or they would never have undertaken the long, hazardous journey across the almost unknown ocean, or braved the dangers, known and unknown, of the wilderness.

Why did they not set up a king, give power and land to barons and aristocrats, volunteer as slaves and serfs and peasants to serve the chosen few, establish a priesthood to tell them what to believe and how to worship? The question answers itself. Not only had they come to America to get away from all that old-world environment, but they varied from their brothers who were willing to stay where they were — and from those with fixed or habit-made ideas about religious freedom and politics. It took scores of generations for this variation to become widely implanted enough to furnish the men and women to start an experiment in government, but when the time came there they were-frontiersmen, makers of a constitution, builders of government, financiers, lawyers, manufacturers, laborers, strong men, weak men, leaders and followers, statesmen and failures, but all containing in themselves the power to make and give permanence to a United States of America!

On and on we go, then, in this wonderful world of ours, one step backward sometimes, then two steps forward, marking time here and making a sudden spurt there — the pear tree, the violet, the animal world, and we humans. Each individual is a little different from the rest, each with a separate combination of old environmental influences stored within him, finding always an infinity of new environments to bring it out, and all of us depending on the others, as we go forward playing each his separate part in the march of progress through adaptation.

Knowing that this infinite variation is to be found in every living thing let us see now how we can use that provision of Nature to add new flowers to our gardens and new colors to the flowers already there.

An architect, in selecting materials for his structure, may send for limestone to Indiana, for granite to Vermont, for hardwoods to South America, for bricks to New York state, for pine and redwood to Oregon and California. In the process of turning his blue-print into a building he draws on the whole world for his materials.

So, in the production of a new flower or color, we must go to the place where the working materials are to be had — in our case, to the store-house of heredity in the plant itself. Of course, if the quality we are looking for isn't there, we are wasting our time. "Do men gather grapes of thorns or figs of thistles?" But Nature has stored in all plants so many possibilities and so many tendencies, perhaps dormant for centuries, that we can do surprising things by taking advantage of those inherent qualities. Our task is to isolate the particular characteristic or "leaning" that goes along with our plan, accumulate it by careful selection and cross-pollination, intensify or multiply it — and presently we have induced the plant to do our bidding.

But we must work with heredity, not against it. True, it is possible to drive a plant against the current of development that is carrying it along, but there are so many flowers and trees and vines and shrubs that are already going our way that it seems extravagant to choose the difficult ones. You may take it is a rule that a habit, whether in a plant or a human, once fixed, grows continually more fixed and set: if you are accustomed to rising at seven you will for a time find it difficult to sleep through till eight or to waken at six; but once you have acquired the six o'clock hour in your sub-consciousness, or the eight o'clock, you will presently find it increasingly difficult to return to seven. Every one who has been governed by the "daylight saving" rule will testify to this. The cactus, which produced its first spines as a weapon of defense, did so with difficulty and took many generations at the job; it was not easy to induce it to abandon spines, even when they were no longer necessary to it; but once that was accomplished and the spineless characteristic was fixed it would be almost as hard to get the cactus to grow its needles once again.

Let us take a practical experiment in color.

We procure first the seeds of two African wildflowers: the African orange-colored daisy, and a white one of the same family. The orange daisy is a sun-loving flower, as its beautiful, rich tint testifies. The white daisy shows unmistakable evidence of having lived for a long time in the shade. But it is easy to see the family resemblance between them. Leaf formation, root development, arrangement and number of rays, stamens and pistils, all bespeak a relationship. The white one is a little taller, more graceful and less hardy, which would serve to indicate that it began by being a sun-plant like its cousin, the orange one.

If we plant the seeds of the orange daisy in the shade it will grow, though not so flourishingly as in the sun, but it will have orange flowers; plant the white one in the sun and it will continue to bear white daisies. That is stored-up heredity, clinging to its latest habits. If either daisy lived, bloomed, went to seed, bloomed, seeded, grew, and bloomed again, and so around the. cycle for many generations we might reasonably expect the two to change colors. Environment gave them their colors; environment could change them. But the process is too slow. We are in a hurry.

ABOVE: Two variants of the Shasta Daisy. Note embryo or rudimentary ray-flowers near the edge of the disks, six being observable on the larger daisy and one quite clear in the left-hand edge of the smaller. Note also the faint "veins" in most of the ray-flowers, indicating that these were once tubular in shape and made up of five petals each.
BELOW: Giant Shasta Daisies, showing the enormous blooming power gained by selection through many generations

Very well; let us take a twenty-foot flower-bed, divide it in the middle, plant one side solid with white daisies, one side with orange, and let the bees and butterflies and breezes combine those differing heredities. We disturb — mix-up — the life-germs of all the resultant seeds; from the millions that develop many will produce white daisies, many orange, some muddy-colored and useless ones, but some with the orange pull predominating over the white and some vice-versa. More than this, since in disturbing the heredities of the two varieties for our purpose (namely, of affecting color), we have stirred up all the latent differences between them, in the second generation and increasingly in later generations we will find ourselves with daisies varying widely in every particular — height, sturdiness, number of blossoms, thriftiness, and all other qualities. And even as regards color we will get unexpected results; for example, some orange flowers may be more deeply orange than any planted; white daisies may appear of a more perfect and waxy white than the parent flowers.

Shasta Daisies, with Mt. Shasta in background. The charming little girl gave this photograph a touch that made it one of Luther Burbank's favorite pictures. He always had a copy on his desk.

We shall, in short, find all of the old inheritances of the flower and of the combinations of them that have ever been in the orange and in the white daisy in the generations and centuries during which they grew apart, the one to become a shade plant, the other to remain in the sun. Now our only puzzle is to pick the color that pleases us best. From the second, fifth, fiftieth, planting — sometime we will get precisely what we had in mind in the way of color.

But it is not at all unlikely that, though the color pleases us, the plant which produces it is not exactly what we consider ideal. It may need to be stronger, taller, more prolific; or the flower, we fancy, might be larger or bear more rays, or it might be one color inside and another out; or it might have a darker or a lighter heart — a smaller or a larger. Very good; then it becomes merely a matter of continuing the experiment, planting selected seed, letting the bees do their work, or taking a hand in it ourselves with artificial pollination, selecting again and re-planting, and so on. Eventually we will be rewarded, not only with the color we set out to get, if it was in the heredity of the original plants, but also with the sort of flower and plant structure, form and thriftiness that meet our needs.

"But," some one asks, "will the seed of this new daisy produce more daisies with the same new qualities?"

Of course not! Not yet! For you must remember that you have deliberately upset the heredity to get this new combination, and the life-germ in its seed is still upset, mixed, disturbed by your interference with the habits of the family. So your ideal daisy will produce perhaps two or three plants with its characteristics and its flowers — the rest of the brood will be regular stepchildren, continuing to amaze you with an infinite variety of peculiarities. At this point we must begin to impress our ideal daisy with its new duties in life; it would tale us many generations; by repetition, repetition, repetition we would, however, get that seven o'clock sleeper to wake at the stroke of six every morning!

With the daisy, as with many plants, there is a short-cut we can take here that greatly simplifies our problem. By dividing the roots of our ideal plant, or by making slips or cuttings from it, we can propagate that very identical plant, itself, without variation in any particular. Presently we have a whole bed of ideal daisies and (perhaps protecting them now from the visits of bees and butterflies who would not know what we were up to and might carry their kind offices too far), we will get second-generation plants with narrowed hereditary influences working on them — tending toward our ideal, you see! — and so in a short time we would find our ideal plants producing seed that, in turn, would produce more and more frequently the ideal plant again. This is that repetition, repetition, repetition which is a refrain with me, because it is another key to "the secret and magic and mystery" of plant-breeding that enables man to train plants to work for him!

Let me take another example of practical work with flowers, leaving fruits and vegetables to later chapters.

In my boyhood days I was very familiar, of course, with the New England oxeye daisy, so prevalent, so hardy, so prolific as to be a pest — a weed. There were, as far as I knew, none of these daisies in California, so I sent for seed from the home-folks and soon had some fine New England oxeye daisies in my garden. It occurred to me to work with them, with a view primarily to developing the size of the flower, so I cast about for a cousin-daisy that would help me, and I lighted on the English daisy, which bears a large, rather coarse flower. Presently I had these, too, growing in my garden; when I crossed the two I found many of my cross-bred plants sending forth blooms that were a considerable improvement on both the parents.

So far, you see, I had some daisy-heredity from rocky, rugged New England, and some from old England. My new daisy plants were sturdy, hardy, luxuriant growers and profuse bloomers, with large flowers.

But there were several faults with them, including a plant-growth that seemed to me too rank for beauty, a tendency to run too much to foliage, and finally, a blossom that left much to be desired in purity and waxiness. Years and years of patient (and expensive) experimentation would have effected an improvement in all regards, but I was looking, as I always have done, for a short-cut.

It was at this juncture that I encountered information concerning the Japanese daisy. I was told that it was a rather coarse plant with an objectionable, leafy stalk, and with flowers so small and inconspicuous as to be scarcely desirable in a garden. But the flower had one quality that I wanted — and the principal one — a pure, waxy white color. Promptly I sent across the Pacific to get my hands on this entirely new bundle of hereditary tendencies, and soon I was busily mixing up the heredity of my oxeye cross with the Japanese blood.

The first results were not wholly reassuring. But in a subsequent season, among innumerable seedlings from this union, one was found at last with flowers as beautifully white as those of the Japanese, and larger than the largest of those that my own hybrid had hitherto produced. Moreover the plant on which this blossom appeared revealed the gracefulness of the New England daisy, and presently demonstrated that it had all the hardihood and thriftiness of both the earlier parents.

From this exciting plant, with its combined heritage of three ancestral strains from three continents, thousands of seedlings were raised each year for the ensuing five or six seasons, the best individuals being selected for seed-bearing and the others all destroyed, according to my custom. And at last I had a flower surpassing all my hopes and expectations — a plant at once graceful enough to please the eye and hardy enough to live in any soil; of such thrifty growth that it reached its blooming time in its first season, though its ancestors had always refused to bear until the second; of such quality and quantity of bloom as to present a glorious picture through a very long blooming season; finally, with flowers from three to six inches in diameter, of crystal whiteness, and borne on long, graceful stems devoid of superfluous leaves.

It was, as I say, a daisy that surpassed my dreamsits name: the Shasta.

It is too long a story to tell here of the varieties of the Shasta that later appeared. It must be sufficient to say that, having stirred up these three remotely related heredities in the experiments, I could scarcely stop the progress, and in time there were growing in my gardens Shasta daisies of the size of dinner plates, daisies with double rays of leaves, daisies with a cream and a yellow color, serrated petals of great beauty, daisies with their petals so curling and ragged that they scarcely resembled their brothers, and an almost countless number of other variations, some of them valuable enough to deserve separate names, which they promptly received, and to be sent out to the world under those other names, among which were the California, the Westralia, and the Alaska.

Yes, we march forward, on and on, step by step, sometimes losing a little ground, next time gaining a good deal in a burst of speed, but always contributing to and participating in the great miracle of evolution. Towards what goal? Ali, that we can not know! But we do see all about us the immediate fruits and results and, in the broadest sense, all of them make the world a better place in which to live!

CHAPTER V
Harnessing Heredity

WE have seen that we can put nothing into a plant that is not contained somewhere in the bundle of its family tendencies, habits and qualities that we call heredity. Therefore the first duty of the plant-breeder is to learn all he can of the laws which govern inheritance in Nature.

There are two which we may well consider at this time, because they are all-important in beginning an experiment. The first is a mathematical determination known as Galton's law; the second is one of the rules formulated by the great student of genetics, Gregor Mendel, which deals with the fashion in which inherited qualities reappear in later generations.

Sir Francis Galton, studying men who came under his observation, noted that a myriad lines of influence converged in every individual, inasmuch as that individual had not only two parents himself to give him inborn tendencies and characteristics, but that they in turn had two each, they two each, and so on back to the very beginning of the race. In other words he came to realize that what a man is at birth can only be determined by inquiring into the lives and characters, qualities and habits, of the two, four, eight, sixteen, thirty-two, sixty-four, one hundred and twenty-eight (and so on indefinitely), of men and women whose blood flows in his veins.

After much inquiry and study he set down as a general rule that the individual inherits approximately one-half his qualities from his parents, one quarter from his grandparents, one eighth from his greatgrandparents, one-sixteenth from his great-great-grandparents, and so on in a mathematically decreasing scale to the beginning of the race. A moment's thought and the contemplation of your own family or a friend's will give you startling proof that here is a profound truth. I have a friend who is tall, rawboned, powerfully built; his father and mother are both of medium height and the father is very slender — almost frail, and has been since childhood. But his mother's father was a big frontiersman, powerful and large-framed. That is as far as I need to go to see Galton's law working out, though I can go much further with my friend and find where he got his blue eyes, his inclination to be an adventurer and wanderer, his aversion to cities, his fondness for music, his ability as a fisherman and hunter, his lack of ability to understand mathematics of the simplest variety, and the fact that his youngest daughter is a natural mathematician!

Presently you see that this rule of Galton's offers an explanation of many manifestations in plant experiments that might baffle and, perhaps, discourage you. For we find our hybrids and seedlings developing wide variations — popping out with forms, habits, dresses of leaves and ornaments of color wholly different from those of either of the parent-plants. When we recall Sir Francis' law we are reassured; here we recognize out-croppings of the heredities of some of those forefather-plants, perhaps many generations back along the line. Instead of being surprised at the variations, we may well wonder why there are not more of them!

Here I should like to trot out a favorite theory of mine that has to do with this subject.

Some of us are very proud of what we call our "family tree" — a drawing that shows us and our cousins and aunts and parents and more remote ancestors all stemming from the trunk of the tree, which is labeled with the name of a great or famous or stalwart old fellow whose blood, we like to boast, is in our veins.

That pet notion of mine is that the family tree is almost useless as telling us anything worth knowing about our ancestry. I maintain that the drawing should be done the other way about: the trunk of the tree should be labeled with your name and, instead of going up into the air, the artist should go down into the ground, drawing the roots of the tree — the sources from which you got your heredity. The farther the artist goes, the more roots he would have to put into the picture. Somewhere deep in the ground below you, you would, of course, find one rootlet labeled with the name of that fine old ancestor of whom you and your relatives are so proud. But there would be hundreds, thousands or millions of other roots and rootlets in the drawing. They would represent all sorts and conditions of men and women, good, bad and indifferent, famous and ordinary, successful and defeated, large and small, blondes and brunettes, and undoubtedly a few red-heads! But they would explain you. They would present a picture of the great stream of heredity that resulted in you and your relatives and that makes you what you are.

But, in studying this upside-down "family tree" I am referring to, as well as in experimenting with plants, you will have to know something of the limitations that Nature seems to have put on hereditary influences — and that is where the Mendelian theory comes in. Let us try to get some glimpse of that principle, even though it be a sketchy glimpse.

Gregor Johann Mendel was an Austrian monk with a garden and a flair for observing Nature and asking questions of her. He was interested to observe that certain characteristics of parent-plants were passed on to the hybrids — the children-plants — and others were not. Yet, in later generations, those missing characteristics would sometimes reappear. Going further, he found that it was possible to entirely breed out some traits and to permanently fix in others. He wondered why and whether there was a law governing the phenomenon.

After a long series of patient experiments he discovered that, in his plants, some characteristics were strong and some were weak; he called them dominant and recessive, respectively. Those dominant traits persisted in coming out; the recessive traits were inclined to give up the struggle and only appear in a few of the later generations of hybrids. In pea-vines, for instance, he found that the tendency to produce round, smooth peas was dominant; the tendency to bear pods containing wrinkled peas was recessive. There was an almost infinite number of these characteristics in peavines, of course. There were dwarf and tall plants, there were those with luxuriant foliage and those with sparse, there were heavy and light bearers, there were those with many peas to the pod and those with few and so on and so on.

Many of these he could "pair off" as occurring in units where one characteristic was dominant, the other recessive. In short, here was a marvelous discovery in genetics, since it gave all breeders an explanation of why certain variations occurred regularly and infallibly, according to a law and not simply by chance.

Starting here Mendel went on to another discovery, namely that the dominant traits would predominate over the recessive according to a pretty fixed pattern in later generations. That pattern it will pay you to study. You will find it explained and diagrammed in any standard text on biology or genetics and, if you want to go very far with plant-breeding experiments in your own garden, you will find the Mendelian theory a useful tool. Here it is only necessary to say that a cross between plants having a pair of those linked-trait characteristics will result in a majority of the hybrids inheriting the dominant characteristic, a few inheriting the recessive characteristic and a small proportion of them inheriting the dominant with a trace of the recessive hidden away in them, to keep reappearing (always according to the pattern) in later generations, clear to infinity.

You see, once you are convinced that a certain desirable trait in your experimental plant is dominant, you can avail yourself of this short-cut to eliminate the opposite trait by destroying the few plants in which the recessive trait shows up. On the other hand, if the trait you think desirable is a recessive characteristic, you know right away that you are going to have a struggle against that dominant tendency and so your experiment will be confined to the use of the far fewer recessive-type hybrids you can expect to get.

Possibly all opposing characteristics in our plant world are actually paired off in this strange fashion, but that we are not yet sure of. And, in thinking of this pattern as a helpful tool, we must remember that every plant with which we deal has an almost infinite number of traits or characteristics. If we are going to think of all of these as falling under the Mendelian law we have a problem so complex as to baffle us. And so we turn to it only when it is definitely helpful and a time-saver to us in our work. And we also recall it when one of our experiments seems to go off at a sudden tangent or when a quality we are seeking disappears inexplicably out of a hybrid which, as we had thought, had that quality impressed on it by its heredity.

I had precisely this experience in my own experiments that led to the development of the white blackberry.

I found reason once to think that a blackberry of a translucent and attractive white color could be produced and I set about the trial. By the usual process of taking advantage of observed tendencies, crossing, growing seedlings, selecting those that seemed to be "going my way," crossing again, again growing seedlings and so on, I developed a fruit like a blackberry in vine-habit and in form, but with white fruits.

But not exactly like, for my white blackberry fell far short of the parent strains in both flavor and sweetness. It was now necessary to go back and try to add these two qualities. To accomplish this I chose as one parent-plant for the next enterprise the large and deliciously-flavored Lawton, took pollen from it and pollinated the white-blackberry blossoms.

The immediate result was the complete disappearance in the hybrid plants of those white berries!

My first thought was, of course, that the characteristic of whiteness was recessive — a natural assumption. But further experimentation convinced me, surprisingly enough, that the newer trait of whiteness in this white-black pairing was dominant, which I soon discovered to be a law. And so, repeating the crossing with the original Lawton, I was rewarded in later generations with white blackberries fully up to my former ones in translucence and beauty but now flavored with the luscious Lawton tang and sweetness.

We are beginning now to get some general knowledge of the way that heredity is harnessed to our purpose in plant-breeding, and of some of the results we may expect when we start practising with living organisms. And while we are on the subject, let us take up a question that has been often asked me, and that may before this have occurred to your mind.

"If what you tell us about crossing varieties is true, and if you can harness heredity to your purposes, why is not the world full of naturally crossed varieties and why are there not constantly developed new plants?" That, in one form or another, is the question to which many people come in this study.

The answer is that crossing of varieties is constantly going on everywhere in the world, and that new varieties are constantly appearing. But, as I have pointed out before, Nature has an infinity of time; she is in no hurry, she has no interest in white blackberries, luscious plums, beautiful pansies, variegated sweet peas, fleeter or stronger horses, one dog that will chase rats and another that will "freeze" into a "point" at a flying grouse or quail; in having a Persian cat different from an Angora, or a canary that can live in a cage and still have the heart to sing and be happy; Nature's first interest is in preserving the species, and that she does very well. We, on the other hand, are concerned with making the individual produce plants more to our liking and we are definitely in a hurry. And so we use Nature's methods but speed them up and direct them toward a different end.

Examine a patch of common "tar-weed" and you will almost certainly find the greatest variation among the plants even in a limited area. Go into the woods and you will find wild flowers of any given variety growing luxuriantly, thickly, with flaming colors on an open place and the same plants smaller, more pale, less plentiful, in shaded glades — two flowers of the same family, but as different as cousins can be different because of their divergent environments. And in between you will find plants that are only half-way in the change — that are compromises which variation and the law of natural selection have made possible, and perhaps able to live either in the sun or in the shade, which neither of their cousins could successfully do.

But presently, in your search, you will awaken to the fact that plants do not cross with totally unlike ones; the rose does not mate with the violet, nor the peach tree with the plum. You do not expect such wide crosses, of course, but do you wonder why they do not occur and whether Nature has a hand in preventing them? Well, you are now on the track of another phenomenon that the plant-breeder must learn more or less about and that he must take into account in his work: the phenomenon of physical and chemical walls which keep species apart. (I have myself succeeded in isolated instances in crossing species, but for our immediate purposes we may take it as Nature's law that they are not expected to, and that many of them absolutely cannot.)

In the first place the physical laws that keep divergent species apart are observable in numerous cases. Almost all species have a different arrangement of the stamen, pistils, corolla, and so on, so that the visitor that can enter one cannot gain access to the other. Also it is well known that insects specialize in visiting certain flowers; even bees, that might take honey from almost any of them, will choose one particular variety and go zooming directly by all the others. That is why we have onion honey, clover honey, orange honey, and so on; for some reason one hive of bees, or a group of hives, will select a cooperative brand and specialize in it exclusively. There are flowers that advertise to accommodate only hummingbirds and will have no traffic with bees or butterflies; there are others with a very limited, accurately timed season when they are willing to give pollen or when they are receptive to it if brought them, and thus another sort of physical barrier is set up between them and their neighbors of a different variety. I could go on indefinitely enumerating these physical walls between varieties and species.

But more important and more generally in use are the chemical walls. We have a great deal to learn about these, still, but we know positively that every living species, or "family" as we call them popularly, has its own peculiar chemical composition or structure, and that you can no more cross the grape and the blackberry, the apple and the orange, the dog and the sheep, the butterfly and the bee, than you can multiply six boys by nine marbles! It just isn't possible, because you are dealing with different things, even though some of them (for example, the poppy and the peony) may, to the casual observer, seem a good deal alike.

Finally, even inside the same variety, where there is no mechanical or chemical bar to a union, we find difficulties often that are due to the fact that the two plants, though related in heredity, have grown far apart in centuries or ages of existence in different environments or with different habits and purposes. In harnessing heredity this is a factor the plant-breeder has to take into consideration. Two varieties of blackberry, for instance, may have stemmed from a common parentage not more than a dozen or fifty or a hundred years ago, but it is plain that the blackberry and the rose, owning common blood ages ago, are now so far separated by habits and practices of growth and their purposes and uses that they would offer more trouble to the plant-breeder, not so much to effect the cross, perhaps, as to effect one that would offer any advantages to us.

These are some of the essential facts important to be known by the experimenter who wants to harness heredities in plants and hitch his team up to do useful or interesting or valuable work. They indicate to us some of the boundaries of our investigation and experimentation; they point out directions in which we can not go. Inside these boundaries again there are, of course, many more limitations, many lines of least resistance to be seized on and many routes of utmost difficulty that are to be avoided. Gradually, as our work goes on, we learn more and more what to do and how to do it; we started in by deciding that we could only work with the tools Nature gives us — heredity and environment — and now we find that she restricts the use even of those tools.

On the other hand she leaves us a field so vast for exploration, discovery, achievement, that it will be a long time before man will more than scratch the surface of the possibilities. So, while we outline the prohibitions and limitations and mention some of the least profitable avenues of research, we know that there remain open to us more ways to train plants to work for man than any of us will ever see exhausted. The world of plant-breeding is our oyster — inside there are still plenty of pearls to be uncovered to enrich mankind and make the old globe a better place on which to live.

CHAPTER VI
Breaking the Rules

IN the previous chapter we agreed that Nature has made some laws and built up some walls that limit and bound the plant-breeder; but now we come to the discovery that man occasionally is mistaken as to what those laws and walls are. When I started my work as an experimenter, spurred on by Darwin, Lamarck, Huxley, Galton, and the rest of those wise men, I was told by botanists that a combination between two varieties of the same species was possible but that crosses between different species were outside the pale of possibility.

A little later on, when I succeeded in crossing the plum and the apricot — parents of undeniably different species — the rules were moved up a peg. It was admitted (grudgingly in some quarters) that it might be possible, under particularly favorable circumstances, to effect combinations between different species, but that combinations between the next higher division — genera — were beyond the power of either man or Nature. And yet, after further study and experiment, I was able to take parents of different genera — the crinum and the amaryllis, for instance — and to bring about successful crosses; thereafter I began to hear less and less about fixed rules and laws.

The fact was, not that I had performed some great magic, or succeeded in smashing the rules, or even in getting them temporarily set aside for my benefit, but that the rules and laws were largely man-made and some of them framed too hastily, without sufficient data, so that I was able to prove them to be nothing more than mistaken conclusions.

As I study it all over I begin to think of Nature's processes as endlessly flowing streams in which varied strains of heredity are ever pouring through the riverbeds of environment; streams that, for ages, may keep to their channels, but each of which is apt, at any time, to jump its banks and find a new outlet. Just about the time we decide that one of these streams is fixed and permanent, there is likely to come along a freshet of old heredity, or a shift in new environment; an overflow occurs, a gap widens in the channel, a flood sweeps over the surrounding field of plant or of life activity — and we must rebuild our bridges and revise all our maps!

Probably, if we take our knowledge of botany as a whole, time will prove that it is pretty generally accurate — that our maps and charts are dependable. In order to know where we are going in this study and to understand what it means when we have to make a new diagram, here and there, let us take a look at the classifications we now have to guide us in the pursuit of the subject of plant life.

To begin with we will have to recognize that truth is only relative, that we can not know all there is to know about so great a subject as life on this planet, that men disagree on innumerable points, and that a great many things are still either not understood or in dispute. For the sake of clearness, then, we will avoid minor divergences of thought and stick to the broad general outline on which most students are agreed. We begin, of course, with the three great kingdoms: animal, vegetable, and mineral. They are fairly distinct; fairly well bounded. Between the inorganic mineral world and the world of sentient and mobile animal life lies the world with which we are concerned in this book — the vegetable.

This world — this kingdom — divides itself into six (perhaps seven) branches called phyla: in the first are found the lowest forms of vegetation — organisms of the simplest type, which reproduce themselves by splitting or division. In this subkingdom are bacteria, which bring about such human diseases as tuberculosis and malaria; or such plant diseases as black rot, and other bacteria that are helpful and lifegiving, such as those that help us digest our food, or that consume otherwise menacing wastes and without whose alliance the higher subkingdoms of plant life could not exist.

The second subkingdom, higher by a step, includes the microscopic vegetables which we call yeasts, those that, through the agency of hops, turn grain juices into beer, those that turn apple juice into cider, and so on. The botanists who prefer to chart seven subkingdoms, instead of six, divide this second phylum into two, giving the "slime molds" a classification of their own.

The third phylum includes mosses and liverworts, among others.

The fourth comprises the ferns-the highest type of flowerless plants, and the first in the ascending scale to exhibit a complete development of root, stem, and leaf. You note here that root, stem, and leaf precede blossom bearing; in other words the ferns are the simplest of our "plants" as we ordinarily think of plants, and they bear no blooms.

The highest phylum or subkingdom contains two branches that have something in common but must be divided because of their seed-bearing habits: these two are called classes, and one is distinguished by bearing its seeds in enclosed organs or packages called ovaries, while the other bears exposed or naked seeds. The first of these classes includes the vast majority of seed-bearing plants; the second principally those trees, like the pine and the cypress, which bear their seeds in open cones.

But in this highest subkingdom, already comprising two classes, we find we have rather more than a handful of growing things, and we divide the classes into orders. The order represents a collection of related families. As an example, the order Rosales is made up the rose family, the bean family, the cassia family, the mimosa family and some twelve others, closely allied.

Below the order, you see, comes the family — a division that is still broadly inclusive, the rose family, for instance, taking in not only our friend, the rose, but the apple, blackberry, and sixty-two other plants whose close relationship might not at first be very evident.

From the family we next narrow down to the genus; here the roads of the rose, the apple, and the blackberry separate, and each begins to take on its own dignity of classification.

Under the genus (the plural is genera ) comes the species.

And the species is made up of varieties.

We have already seen that the simpler the form of life, the less tendency there is to variation; as we get higher in the scale we find those variations increasing and making it more and more difficult to put the multifarious varieties into pigeonholes of classification where they exactly fit; it is for this reason that there is a wide divergence of opinion among scholars and scientists concerning names of things and labels for groups. But with that argument we have, here, nothing to do. Our concern is to observe immediately that there is one certainty in the world of plants, even though there may be only one!

That certainty is that the individual plant is something on which we can put our fingers — ; if we but watch it and give it an opportunity, it will speak for itself, beyond dispute or denial, telling us what manner of plant it is and just what we may hope for it and expect of it. When we learn this fact we realize that, after all, classifications, theories, indices, learned discussions — all these are created by man; but the individual plant is created by Nature, or by God, or by Evolution — however you choose to phrase it! — and is a sure and certain beginning for our study and our work.

In this book we are studiously avoiding scientific formulas and dogma and scientific jargon and technical expressions, because it is planned as a practical book. But it will make it easier for the reader if we make one concession to science and follow, the scientific method of labeling the plants we are writing of. This scientific language, as most of you know, is Latin, because scientists all over the world employ it and therefore can understand one another readily.

Now, as to the scientific names of plants, observe that no mention is made of class, order, or family. The first name is the name of the plant's genus.

The name of its species follows.

And the name of the variety, if given, comes last.

Thus, in writing the name of an apricot, a plum, or a cherry, we should first set down its genus name: Prunus.

If our fruit (say, a cherry) were of the species Avium, the Latin designation becomes Prunus Avium.

But, if we want to specify a particular variety of the cherry, as, say, the Mayduke, we would set down the full title thus: Prunus Avium Mayduke. And, finally, to save repetition, if our chapter or our article concerned cherries only, we would, after the first naming of the variety, thereafter write P. Avium Mayduke, taking it for granted that P., to the reader, would always mean Prunus until we changed the subject.

Now, having made that aside in order, to clarify things, let us go back to this subject of the Breaking of Rules with which this chapter is concerned. I use that title because that is the mistaken notion many people have of the work of the plant-breeder — that he is "breaking the rules" of Nature in "training plants to work for man." As a matter of fact, as I have hinted above, there is no such a thing possible as the breaking of Nature's laws, for they are immutable and unchangeable. What is possible, and what we do every day, and what Nature herself simply delights in doing, is the breaking of rules that men make and try to pass off on the world as natural laws. Natural fiddlesticks! They are only human guesses as to what the true facts are! And so, of course, they are broken constantly, and have to be revised constantly, and often have to be discarded altogether as out-moded, or false, or insufficient.

One of the most hopeful and encouraging evidences of our progress in free thought and in civilized progress is the evidence we see all about us that men are very rapidly recognizing the truth of what I have set down above. Only a few centuries ago such a statement as I have written would have caused me to be burned at the stake, I suppos