/"/7CP Mam Li* LUTHER BURBANK GATHERING POPPIES. The selected varieties of red oriental poppies blossom early and late at Sebastopol. This piclure was taken in March, 1914, not long after Mr. Burbank's sixty-fifth birthday. It is an excellent portrait of the plant developer as he is to-day. LUTHER BURBANK HIS LIFE AND WORK By HENRY SMITH WILLIAMS, M.D., LL.D. AUTHOR OF "MODERN WARFARE," "ADDING YEARS TO YOUR LIFE" ; EDITOR IN CHIEF OF THE LUTHER BURBANK SOCIETY ILLUSTRATIONS IN COLORS AND BLACK AND WHITE FROM PHOTOGRAPHS NEW YORK HEARST'S INTERNATIONAL LIBRARY CO. 1915 Copyright, 1915, by HEARST'S INTERNATIONAL LIBRARY Co., INC. All rights reserved, including that of translation into the foreign languages, including the Scandinavian ^ / r/7 • * %,«• . 5/3*3 CONTENTS CHAPTER PAGE INTRODUCTION ... . . . ix PAET I LUTHER BURBANK THE MAN, AND AN OUTLINE OF HIS METHODS I LUTHER BURBANK: THE MAN AND His WORK . . . . . . .3 II THEORIES OF PLANT DEVELOPMENT . . 24 PART II WITH LUTHER BURBANK IN ORCHARD, GARDEN, FIELD, AND FOREST III THE CARE OF SEEDS AND SEEDLINGS . 45 IV WITH BURBANK IN THE ORCHARD . . 56 V NEW BERRIES AND GARDEN FRUITS . 80 VI BURBANK IN THE VEGETABLE GARDEN . 107 VII BURBANK IN THE FLOWER GARDEN . . 131 VIII THEORY AND PRACTICE . . , . 156 IX BURBANK 's METHOD OF BEAUTIFYING LAWN AND DOORYARD .... 170 X BURBANK 's WAY WITH TREES . . 206 [v] 393739 CONTENTS PART HI BURBANK'S METHODS AND THE HUMAN PLANT CHAPTER PAGE XI THE BEEEDING OF MEN .... . 239 XII THE LAWS OF HEEEDITY — THEIR DEFI- NITE MEANING AND INTERPRETATION . 262 XIII NURTURE versus NATURE . . 295 [vi] LIST OF ILLUSTRATIONS Gathering Poppies (color) . . . Frontispiece TAC1NO PAGE A Cluster of Burbank Plums 8 A Group of Stoneless Plums 16 A Fruit-bearing Slab of Spineless Cactus . . 24 Mr. Burbank Inspecting a Choice Variety of Spine- less Cactus . 32 A Field of Spineless Cactus at Santa Kosa . . 40 Spineless Cactus in Fruit . . . . .48 Boxes of Seedlings in Mr. Burbank 's Conservatory 56 Mr. Burbank Inspecting Cross-bred Tomato Seed- lings . . . 64 The Culture of Seedlings at Santa Rosa . . ;•: 72 A Cleft Graft (color) .80 Cultivating the Fruit Orchards .... 88 The Process of Grafting Completed .... 96 A Brand-new Burbank Fruit — the Plumcot (color) 104 Mr. Burbank 's Phenomenal Berry .... 112 Mr. Burbank 's White Blackberry (color) . . 120 The Burbank Thornless Blackberry .... 128 Inspecting Hybrid Blackberries . . . . 136 Mr. Burbank 's Himalaya Blackberry . . . 144 Mr. Burbank Inspecting Garlic Seedlings . . 152 The Camassia — a Flowering Food Plant . .160 Burbank 's Onions Grown for Seed (color) . . 168 Mr. Burbank Planting Choice Seeds . . . 176 A Burbank Hybrid Tigridia (color) V. . . 184 A View of Mr. Burbank 's Garden at Sebastopol . 192 [vii] LIST OF ILLUSTRATIONS PAGE Beds of Shasta Daisies 200 Quantity Production Applied to the Watsonia . 208 A New Burbank Eose 216 An Interesting Variety of Evening Primrose . . 224 A Burbank Hybrid Dahlia (color) .... 232 Rows of Hybrid Amaryllis 240 One of Mr. Burbank 's New Varieties of Giant Amaryllis . 248 A Gigantic Bulb 256 Quantity Production Applied to the Australian Star Flower 264 A Miniature Chestnut Tree 272 A Dwarf Chestnut (color) 280 Grafting Fruit Trees at Sebastopol .... 288 Hybrid Massachusetts Elm on California Roots . 296 A Fine Specimen of the Royal Walnut . . . 304 Variation Among the Canes of Seedling Briars . 312 [viii] INTRODUCTION EVERYONE knows that marvelous work in developing new forms of plant life has been performed by Luther Burbank at Santa Rosa, California. Indeed, the name Burbank is a household word. And yet when you come to question people as to their precise knowledge of what Mr. Burbank has done, you find that, as a rule, their information is singularly vague. They may have heard of the Burbank potato, the stone- less plum, the Shasta daisy, the white blackberry, or the spineless cactus. But something like this is pretty sure to be the full measure of their knowledge as to the Santa Rosa experimenter's specific accomplishments. This is not strange, for until recently there has been no authoritative and comprehensive account of just what Mr. Burbank has really done, much less how he does it. Now, to be sure, Mr. Burbank 's own account of his lifework is available in twelve large vol- umes with more than twelve hundred illustrations, all in color. There is no longer any reason why the critic should be in doubt as to just what Mr. Burbank has done, just what are his theories and methods. But of course not everyone has yet seen the comprehensive work in question, so it still seems desirable to give a briefer account of [ix] INTRODUCTION the methods and results of the Santa Eosa ex- perimenter. This is done in the present volume, which, obviously, makes no pretense to compete with the series of volumes just referred to, as issued by the Luther Burbank Society ; but which might rather be considered as preliminary or sup- plementary to those volumes. Some readers of these pages, I trust, will be stimulated to seek at first hand the pages of the larger work, to read extensive accounts of things that are necessarily treated here with brevity or barely referred to. And, on the other hand, it is not unlikely that some possessors of the larger work may find the present volume a convenient summary, serving the purposes of recapitulation. It should perhaps be explained that Mr. Bur- bank is in no wise responsible for the present book, except in the sense that his work furnished the foundation for it. Mr. Burbank must not be held responsible for any theories or statements herein made, unless particularly accredited to him. But, as evidencing the authenticity of the main presentation of his theories and the chief summary of his work here presented, it is per- missible to recall that the writer has acted as editor-in-chief of the series of volumes above re- ferred to, and that in that capacity he has had access to all Mr. Burbank 's original manuscripts and records, in addition to spending several weeks in close personal communion with the plant developer himself at Santa Eosa, every aspect of INTRODUCTION his work being the subject of detailed and elab- orate discussion. The illustrations of the series of volumes issued by the Luther Burbank Society — bearing title "Luther Burbank: His Methods and Discoveries and Their Practical Application " — constitute probably the most remarkable set of color pic- tures ever published in connection with any single work dealing with plant life. They are 1260 in number, reproduced in the main from direct color photographs made on Lumiere plates ; and they show every aspect of Mr. Burbank 's work, and typical specimens of his achievements in plant development. We are permitted to reproduce eight of these pictures in the present volume, through courtesy of the Luther Burbank Society. A glance at these will give the reader some intimation of the sumptuousness of the almost endlessly varied mass of color illustrations from which these are excerpted. The black-and-white illustrations of the present volume are partly from other photographs be- longing to the Luther Burbank Society, and partly from original photographs by the author, who has perhaps put Mr. Burbank 's unfailing good humor to severer test by his persistent use of the camera at Santa Rosa and Sebastopol than it was ever otherwise similarly tested. For the famous ex- perimenter is a very modest man, and the sight of a camera fills him with trepidation. Fortu- nately, however, he is as accommodating as he is [xi] INTRODUCTION modest, and as the writer was given permission to make snapshots quite without restriction, we are able to present unique views of Mr. Burbank in action — views that will be highly appreciated by plant lovers who have not been privileged to visit Santa Rosa in person, and to whom the per- sonality of the famous experimenter is the sub- ject of legitimate interest. It will be seen that the subject-matter of the present volume is divided into three parts : the first dealing with the life and personality of Mr. Burbank, and with an outline of his theories ; the second with a detailed treatment of his practical methods as applied in orchard and garden and field and forest ; and the third with an attempt to interpret his work in its possible application to what he has picturesquely spoken of as the breed- ing of the human plant. The last-named subject carries us somewhat afield from Mr. Burbank 's direct activities, but it deals with matters of obvi- ous importance, and matters in which Mr. Bur- bank himself takes the keenest interest. It should be added that the chief part of the matter in- cluded in this concluding section of the present work has appeared as a series of monographs is- sued by the Luther Burbank Society (distributed to its members only), and is reproduced here by courtesy of that organization. [xii] LUTHER BURBANK PAET I LUTHER BURBANK THE MAN, AND AN OUTLINE OF HIS METHODS CHAPTER I LUTHER BURBANK: THE MAN AND HIS WORK WE naturally think of Luther Burbank as a Calif ornian; but in point of fact the celebrated plant experimenter was born and reared in Massachusetts. The little town of Chester was his birthplace, and he grew to ma- turity on his father's farm in daily contact with nature in her somewhat primitive aspects. Mr. Burbank has himself called attention, not without amusement, to the fact that he was his father's thirteenth child; and he has used this fact to give whimsical support to his own familiar method of "quantity production" in plant breed- ing, pointing out that no one of the first dozen children of his fraternity showed any particular propensity to devote attention to plant develop- ment, and drawing therefrom the serious conclu- sion that the full potentialities of any hereditary strain cannot be realized unless the old-fashioned custom of having large families is practiced. It is a moral worth giving sober attention, in these days when the Colonial stock, of which Mr. Burbank himself furnishes a rather typical ex- ample, is relatively dwindling, to the detriment — at least so some of us think — of our civilization. [3] LWT&ER BURBANK Lnth&r Surbank was a rather frail child, though not without abounding physical vigor. He was of a thoughtful, studious bent of mind, with an inherent love of flowers and plants that mani- fested itself at a very early age, and with an almost equally striking fondness for mechanics. It is recorded that one of his most fondly prized toys in infancy was a specimen of spineless cactus, and that the possession of a flower would almost always quiet him and give him, seemingly, greater pleasure than he derived from any other kind of toy. His inventive bent manifested itself very early, and led him to the devising of many mechanisms, including a home-made steam engine, which he used to propel a boat, producing thus a prototype of the modern motor boat half a century before that craft gained popularity. The most conspicuous application of young Burbank's mechanical genius, however, was made in a factory where he went to work just as he was verging on maturity. This was a labor- saving device of such usefulness that it enabled him to multiply the efficiency of his work tenfold, so that his earnings, which at first had amounted to only fifty cents a day, quickly mounted to a really respectable figure. He might have re- mained indefinitely in the factory, with the assur- ance of a good salary ; but the confinement proved unhealthful, and he soon returned to the fields, never thereafter to leave them. [4] THE MAN AND HIS WORK LUTHER BURBANK 's EARLY EXPERIMENTS The inventive genius hitherto applied to me- chanical apparatus was now transferred to the living plant, and from the outset young Burbank began experimenting along new lines even in car- rying out the most commonplace work of the gar- dener. For instance, he found a way to force the development of his sweet corn by sprouting the seed in a hotbed and dropping the young plants into hills in the open as if they were mere seed kernels ; and he performed a great variety of in- teresting experiments in the cross-fertilization of different races of beans, of sweet corn, and of various other garden products. Nothing strikingly notable came of this work, however, until an occasion when the experimenter discovered a seed ball on the vine of an Early Rose potato; saved the twenty-three seeds that the ball contained, and grew from each of them a hill of potatoes next season. The twenty-three hills were in a single row, and were given pre- cisely the same attention, yet each produced a quite different type of tuber ; and one of the hills revealed a large cluster of potatoes of such ex- ceptional size and smoothness of contour and quality of flesh as to be very notable. This was the potato which the young experi- menter sold next season to a practical gardener, who gave it the name of the Burbank potato. It was estimated several years ago by the au- thorities of the Department of Agriculture at [5] LUTHER BURBANK Washington that more than seventeen million dol- lars' worth of Burbank potatoes had been raised in the United States since the variety was intro- duced. The producer himself received only one hundred and fifty dollars for his prize. The money sufficed, however, to pay his fare across the continent, and enabled him to carry out his ambition to migrate to a climate better suited to the purposes of the plant developer, — for he had long since determined to give his life to this work. THE MIGEATION TO CALIFOKNIA Arriving in California, Mr. Burbank selected Santa Rosa as his residence, and this has con- tinued to be the seat of his activities to this day. The migration was made in the year 1875. At that time the potentialities of California as a fruit-growing state were not very fully realized, and it was by no means easy for a young man without capital to establish himself in the prac- tical business of a nurseryman, which was Luther Burbank 's immediate ambition. Before he could carry out this ambition, it was necessary to serve an apprenticeship of two or three years, during which he turned his hand to any work which pre- sented itself. He developed skill as a carpenter, and he continued to earn a living at that trade for some time after he had established a nursery by way of avocation. Those were trying years; but Yankee thrift, energy, and perseverance finally prevailed over [6] THE MAN AND HIS WORK all obstacles and within four or five years after coming to California Mr. Burbank found himself in possession of a commercial nursery that netted him an annual income of about ten thousand dollars. His orchard products were mostly of standard varieties, but he had applied to them from the outset the selective skill that was to make him famous, and he had gained for his seed- lings a reputation for reliability that caused them to be bought by would-be orchardists throughout the fruit-growing region. Such commercial success as this was gratifying, but Mr. Burbank regarded it as only a stepping- stone. Even while his chief time was necessarily given over to the practical duties of the nursery- man, he found opportunity to make numberless experiments in hybridization and selection among the various plants in his nursery ; and so soon as his financial affairs gave the least promise of se- curity, he had cast about for a piece of land on which he could establish an experiment garden to be devoted exclusively to the production of new and improved varieties of plants of every type. He found four acres that could be made avail- able by proper drainage and fertilization, in the town of Santa Rosa, and there he established the garden that was soon to be famous as the seat of the most remarkable series of plant experiments that have been carried out in our generation. A little later he purchased a tract of eighteen acres at Sebastopol, seven miles away, where the topo- graphical and climatic conditions were slightly [7] LUTHER BURBANK different. There his main experiment orchards were established, and opportunity was afforded for the carrying out of the idea of "quantity pro- duction" more effectively than was possible in the restricted area of the Santa Eosa garden. From that day to this, Mr. Burbank has con- ducted his experiments on these two plots of land, aggregating about twenty-two acres. Within this relatively small area more than a hundred thou- sand distinct experiments have been carried out, involving five or six thousand species of plants, and numberless varieties, the original seeds or stocks or roots of which have been sent to Mr. Burbank from all parts of the world. Probably there is no other similar area of the earth's surface that has seen a corresponding variety of vegetable products in the same time; certainly there is no other that in our day has produced such a galaxy of new and wonderful plant products as have grown in the experiment gardens at Santa Eosa and Sebastopol. NEW APPLICATION OF OLD METHODS The fundamental principles of plant develop- ment through which Mr. Burbank thought to de- velop new and improved varieties were not in themselves novel or revolutionary. They con- sisted essentially in the careful selection among a mass of plants of any individual that showed ex- ceptional qualities of a desirable type ; the saving of seed of this exceptional individual, and the [8] THE MAN AND HIS WORK carrying out of the same process of selection among the progeny through successive genera- tions. Couple this method of selection and so-called line breeding with the method of cross-pollenizing different varieties or species, to produce hybrid forms showing a tendency to greater variation or to the accentuation of desired characters, and we have in outline the fundamental principles of plant breeding as known to horticulturists for generations, and as applied by Mr. Burbank from the outset of his career. But there were sundry highly essential details of modification that were introduced by the Santa Rosa experimenter, as will appear presently. Moreover, even in the application of the old familiar method, Mr. Burbank was able from the outset to gain exceptional results because of cer- tain inherent qualities that peculiarly fitted him for the work. Among these qualities was his ex- ceedingly acute vision, a remarkable color sense, and almost abnormally developed senses of smell and taste. Artists who have tested his eyes have declared that he can readily detect gradations of color that to the ordinary eye show no differentia- tion whatever ; and it is a matter of hourly demon- stration that he can ferret out an individual flower having any infinitesimally modified odor in the midst of a bed of thousands of such plants, almost as a hunting dog detects the location of a grouse or partridge under cover. Similarly his exquisitely refined sense of taste [9] LUTHER BURBANK guides him in selecting among thousands of in- dividual plums or cherries or grapes or apples or berries the one individual specimen that has the most delectable flavor or that shows a minute modification of flavor in the direction in which he is endeavoring to modify the variety. This almost preternatural endowment of special senses is supplemented by a knowledge of the co- ordination of parts — say between the stem or leaf and the future fruit of a plant — that is so pene- trating and mystifying as to seem intuitional and to suggest occult powers of divination. As an instance, you may see Mr. Burbank strid- ing along a row of, let us say, plum seedlings com- prising some thousands of plants perhaps a foot high. He seems to inspect the little trees but casually, except that now and again he pauses for a moment to indicate with a motion of his hand that this or that plant has particularly attracted his attention. A helper, or more likely two helpers — for one can scarcely keep up with the energetic leader — will be at hand to note the sig- nals ; and a bit of white cloth will be tied about each successively selected seedling ; or two pieces of cloth, or even three, in case an individual has seemed to show quite exceptional promise. And with that, one stage of the work of selec- tion is finished. Perhaps ten thousand seedlings have been passed in review in a half-hour, and conceivably fifty or a hundred have been selected for preservation. These have shown to the keen scrutiny gf the plant experimenter such qualities [10] THE MAN AND HIS WORK of stem and bud and leaf as to forecast the type of fruit sought to be developed in this particular experiment. The entire rows of seedlings are the product of hybridizing experiments and antecedent selec- tion extending perhaps through many generations. The seed from which they were grown has been carefully gathered and treasured, and infinite pains have been taken to bring the seedlings, through transplantation and cultivation, to their present stage of development. Yet now, in a single half -hour, they have been made to run the gauntlet of a vision that seems to penetrate to the very heart of their germ-plasm, like an X-ray, and all but a bare half-dozen or so in each thousand have been found wanting. Another hour, and the ten thousand failures — less the half-hundred — will have been uprooted and piled in a heap to be burned like any other mass of rubbish. They had done their best, but their best was not good enough; and the soil that they occupied must be given over to some other line of experiments; for every acre of these gardens must be made to do the work of a score of acres. Meantime the dozen or score of selected seed- lings that remain as the lone survivors here and there in the devastated ranks will be treasured and be given every horticultural attention. At the proper season they will come under the knife of the grafter, who will cut each stem into appro- priate sections and graft pieces on the limbs of some sturdy tree of the same species. This is [11] LUTHER BURBANK done to hasten their development, for Mr. Bur- bank has discovered that stems thus grafted will come to bearing much earlier than if left on their original roots. Time is precious, particularly when we are dealing with plants of such slow growth as the fruit trees, and it is obviously worth while to save a year or two, as is thus possible; for at best an experiment in the development of a new type of fruit must be carried out, as a rule, through a good many generations, making significant encroachments on the working life of the plant experimenter himself. Where such a method as that just outlined is carried out, it is obvious that everything depends upon the skill with which selection is made. A man lacking Mr. Burbank's "intuitional" skill in such a selection would inevitably go wrong. His experiments would come to nothing. He would inadvertently destroy the best and preserve the worst. By no mathematical chance could he select the right dozen or score of individuals among the tens of thousands. But that Mr. Burbank is able to make such se- lections with a correctness that is little less than weird has been demonstrated again and again through tests in which various of the discarded seedlings have been preserved and brought to fruitage for comparison with the selected ones of their fraternity. Always the selected individuals show more of the quality that is being sought than is shown by the specimens taken from the discard; thus jus- [12] THE MAN AND HIS WORK tifying a forecast that was made so readily with such seeming facility as to appear almost necro- mantic. In point of fact, the plant experimenter was exercising no occult powers but only trained senses backed by an amazing fund of practical knowledge. He was looking for stems of a par- ticular size and ruggedness of contour ; for leaves that were symmetrical, right-hued, and thrifty; for buds that were plump and fat and of just the right color. But his eye took in the details so quickly and his conclusions were reached with such seemingly automatic precision, that the en- tire procedure took on a mystifying aspect of wizardry. With such exhibitions of his skill constantly in evidence, it is not strange that Mr. Burbank should have become traditional among his own contemporaries as the "wizard of Santa Rosa"; although the worker himself has always ardently deprecated any such characterization, calling him- self a "plant experimenter," and being foremost to affirm that what he accomplishes is done by careful study of the laws of heredity, ceaseless scrutiny of the physical qualities of plants in their every aspect, and the definite application of knowledge gained through thousands of ante- cedent experiments. The range and scope of these experiments, it may be added, are no less astounding than the manner in which they are carried out. There is scarcely a tribe of plants showing any promise [13] LUTHER BURBANK whatever of development of its stock or root or flower or fruit and having the remotest prospect of thriving under the climatic conditions of Santa Rosa and Sebastopol that has not been tested by specimens brought from one corner or another of the world — from both hemispheres and from every continent — and set to work in Mr. Bur- bank's training school. To give the names of the different species and varieties that have here been modified and improved through selective breed- ing— quite overlooking the other legions that have proved recalcitrant — would require many pages. So I must be content with the citation of only a few of the more conspicuous examples. NEW FBUITS FOB OKCHABD AND GAKDEN Consider, for example, the orchard fruits. Mr. Burbank has produced almost numberless new varieties of apples, pears, peaches, apricots, plums, prunes, cherries, and quinces. He has in- troduced more than sixty new varieties of plums and prunes, combining the strains of ancestors from Europe and Japan with those of our native species, and producing an extraordinary company of fruits of the most varied qualities. Here, for example, are prunes that are not only of gigantic size and borne in profusion, but which have a quality of ripening in midsummer and of developing a greatly increased sugar content. Here are plums that add to their other qualities the capacity to withstand shipment across the con- [14] THE MAN AND HIS WORK tinent, or for that matter round the world. Here is one plum that looks and tastes like an apple and another that has precisely the quality of a Bartlett pear. And here are plums and prunes that while exteriorly looking like other fine speci- mens of their kind differ essentially from all others in that you could bite right through them as you bite through a strawberry, because they are stoneless. And then, most marvelous of all, here is a fruit that had a plum for one of its ancestors, but for another ancestor an apricot; a strange hybrid which, in recognition of its origin, was named the "plumcot" and which constitutes a brand-new type of orchard fruit, the first addition that has been made to the familiar list within historical times, and the only orchard fruit whose origin is definitely known. This one was created at Se- bastopol, as the result of a long series of tests in cross-pollenizing the plum and apricot; tests which at first seemed doomed to failure, but which ultimately culminated in the production of a won- derful new fruit. In the small-fruit garden, Mr. Burbank has de- veloped many highly interesting new forms, some of which are entitled to rank as new species. There is, for example, the Primus berry, a cross between the dewberry and the Siberian rasp- berry; the Phenomenal berry, a cross between the dewberry and the Cuthbert raspberry; and the Paradox, a cross between the Lawton black- berry and the crystal white blackberry. [15] LUTHER BURBANK Then there are luscious blackberries that are pure white, and others that grow on vines that are as free from thorns as the twigs of an apple tree. Also there is the sunberry, a palatable fruit produced by combining the traits of two inedible nightshades, and there are numerous new varieties of strawberries, huckleberries, currants, gooseber- ries, and elderberries, as well as sundry rare ex- otics that will claim our attention in due course. NEW VEGETABLES AND FLOWEES In the vegetable garden, Mr. Burbank achieved his earliest success through the production of the Burbank potato, the full story of which will be told presently. He has worked effectively with all the familiar types of garden vegetables, his efforts culminating, perhaps, in the development of the now celebrated Crimson winter rhubarb, the an- cestor of which came from New Zealand. Among thousands of experiments with flowers it is hard to choose, so many and so notable are the developments. The Shasta daisy, which com- bines the strains of species from Europe, from Japan, and from America, has exceptional inter- est both from a scientific and from a popular standpoint. But scarcely less interesting are the hybridizing experiments through which were pro- duced the giant amaryllis with its nearly twelve- inch blossom, the spectacular tigridias, the scented callas, dahlias, and verbenas, the beautiful wat- [16] A GROUP OF STONELESS PLUMS The original from which Mr. Burhank's numerous stoneless plums developed, is a Euronean fruit no larger than the smallest of the above specimens. The picture illustrates the variation among seed- lines, and the remarkable development in size of the better varieties, brought about through cross-breeding. There is a corresponding im- provement in the quality of the fruit. THE MAN AND HIS WORK sonias and gladioli, the wonderfully varied pop- pies, including one that is blue in color, and the extraordinary colony of lilies showing thousands of new and strange combinations of form and color. By way of adorning lawn and park, Mr. Bur- bank has developed a substitute for grass in the South American lippia which thrives in time of drought, and requires not one-tenth the attention given ordinary lawn grass. He has developed a vast number of ornamental shrubs and vines, in- cluding new types of clematis with beautiful and varied flowers. And in experimenting with trees he has produced walnuts that grow to gigantic size in a few years, and, at the other end of the scale, chestnuts that bear abundant crops when they are mere bushes. A chestnut that bears large nuts at six months from the seed creates as much astonishment as almost any other single anomaly seen at the fa- mous experiment gardens at Sebastopol. The chestnut that is developing a smooth burr is also of peculiar interest; matching the walnut that was made to bear so thin a shell that the birds destroyed the nuts, so that it became neces- sary to thicken the shell by further selective breeding. These glimpses, together with bare mention of the spineless cactus with its amazing crop of luscious fruit, must suffice to suggest the varied lines of plant experiment that Mr. Burbank car- ries forward year by year. [17] v LUTHER BURBANK We shall have occasion to inquire just how some of these extraordinary anomalies in plant life were produced in the course of our examination of the special theories of plant development that have guided Mr. Burbank in his elaborate and fruitful experiments; and fuller details will be given in the chapters making up Part II of the present volume. BURBANK METHODS AND THE HUMAN PLANT A man of Mr. Burbank 's philosophical cast of mind could not fail to give a vast deal of thought, first and last, to the question of a possible appli- cation of knowledge gained in the experiment gar- den to better development of the human race. In point of fact, Mr. Burbank has not only thought but has written and talked on the subject very extensively. He has very pronounced ideas about the development of the human plant that are the outgrowth of his experimental studies with plant life. Nowadays we all understand that the same gen- eral principles apply to all types of living crea- tures. With the proper allowance for details of variation, the laws of heredity studied in the vege- table garden can be applied with much assurance to the breeding of animals or the betterment of the human race itself. So large a subject cries out for extended treatment, but it is obvious that in the space available here I can do no more than make brief reference to the possible application of [18] THE MAN AND HIS WORK the principles of plant breeding, as Mr. Burbank interprets them to the human race. At the very outset, we are met with obvious difficulties. Mr. Burbank selected only good stock from which to breed. He saves ten or a dozen plants from a bed of thousands and tens of thou- sands. Obviously no such restriction is possible in the human family, even were we to put into effect the most sweeping conceptions of the eugenist. But Mr. Burbank optimistically calls attention to the fact that the civilized races of to-day are in effect highly selected stock. They are the result of many centuries of breeding during which so- ciety endeavored to rid itself of undesirables. Capital punishment for minor crimes doubtless had an appreciable eugenic influence; and under the pampering conditions of city life, disease decimates the ranks of the weaklings; even wars tend on the whole to remove individuals of less evolved mentality. So, on the whole, such a stock as the average American race is a highly evolved and selected type, in large measure adapted to its environ- ment, and eminently fit for propagating the species. But of course some members are better fitted than others to carry out this function; and at present there is an unfortunate tendency for the better members to have small families while the less desirable ones have large families. It per- haps does not need the advice of the Santa Rosa [19] LUTHER BURBANK experimenter to tell us that this propensity, if not checked, must lead to disaster, but his experi- ence may be cited as emphasizing the lesson. Unless the more desirable members of a race can be made at least as prolific as the less desir- able ones, that race must deteriorate. In this connection, the enormous immigration of recent years, made up largely of individuals of a less evolved type (as illustrated by the fact that thirty-five per cent of the membership of the "new immigration" cannot read or write), becomes a possible menace. Twenty-seven million immi- grants have come to us since 1860 — that is to say, during two generations. Mr. Burbank feels well assured that so large an increment of new blood must directly modify the character of our race; and he is at one with many sociologists in ques- tioning whether the increment of new germ-plasm has been, on the whole, of a type to prove bene- ficial. Of course even an illiterate immigrant might bring certain qualities — say a musical or artistic sense — that would be advantageous for blending with American racial strains; somewhat as Mr. Burbank 's inferior little French plum had one important quality of stonelessness that made it valuable. But it must be recalled that Mr. Bur- bank was obliged to instil a preponderant influ- ence from valuable strains of plants to the point of entire elimination of the poor qualities of. the original stoneless variety. Without this instilla- tion of good qualities, he could never have pro- [20] THE MAN AND HIS WORK duced a stoneless plum having commercial value. Similarly, it will be necessary to overbalance the undesirable qualities of the unevolved immigrant by a preponderance of good blood if we are to make use of his desirable qualities. From this point of view, then, the same ques- tion is emphasized: The better stock of America must be induced to reproduce itself more abun- dantly than has been its custom of late, or the infusion of immigrant blood of the type that is coming to us will be ultimately harmful. As to the rearing of the human plant in its early stages — that is to say, the care of the child — Mr. Burbank has ideas that are equally pro- nounced; and here he is able, perhaps, to make more directly tangible applications of his studies in the field. As a practical horticulturist, he has been called upon thousands of times over to ob- serve that everything depends upon the treatment that the seedling receives the first few days or weeks of its life. He takes infinite pains to pro- vide just the right soil, just the right conditions of moisture and sunlight and shelter from the wind; and he has seen it demonstrated times with- out number that the weal or woe of the future plant, whatever its heredity, is largely determined by this early treatment. Making application to the human plant, he be- lieves that few people fully understand how largely the body and mind of the child are molded by the environing influence of infancy. He urges very strenuously that life should be made agree- [21] LUTHER BURBANK able for the young child; that it should be kept in the open, allowed to play, to come in contact with nature, to do the things in which childhood naturally delights. He would have no child sent to school until it is nine or ten years old, believing that the educa- tion of the playground and field is better than the education of the schoolroom during this early period. And when the child has reached the school age, he would have its tasks made less laborious and exacting than they sometimes are. He would pay heed at all stages to the child's bodily development, knowing that fine blossoms do not come from dwarfed plants. In a word, he would make the environment of childhood and adolescence healthful and stimu- lative and pleasure-giving — comparable to the en- vironment that he supplies for his seedling plants. Only by doing as he does can Mr. Burbank secure the best results with his plant proteges ; andxonly by a comparable line of action, in our treatment of the child, so he believes, can we count on mak- ing the most of the coming human generation. Mr. Burbank 's love of children is comparable to his love of flowers. It^was^ peculiarlyappro- priate that the Legislature of have sH^^e^JiOiHEdS^lhe ninth_of^tarch, as a school holiday to be known^s j?orbank Pay. On that day each successive year the school chil- dren of Santa Rosa" come to pay their respects to Mr. Burbank in jperson ; and he has received as [22] THE MAN AND HIS WORK many as four thousand letters at once congratu- lating him on the occasion from the school chil- dren of other^ cities and even of distant states. To see Mr. Burbank on his doorstep sur- rounded by a group of school children is to see him as happy as when he is in his garden amidst beds of rare and beautiful flowers. No sketch of the Santa Rosa plant developer would be com- plete that did not refer to this aspect of his inter- ests and give emphasis to this phase of his per- sonality. In Part III of the present volume we shall have occasion to treat somewhat in detail the question of the possible application of Burbank methods and allied biological data to the improvement of the human plant. But we must first study the methods themselves and their direct application in the gardens of the Santa Eosa experimenter. [23] CHAPTER II THEORIES OF PLANT DEVELOPMENT FIRST, last, and all the time Mr. Burbank is a practical plant developer. But it would have been quite out of the question for a man of his energetic and active type of mind to have gone about his experiments without theoriz- ing constantly as to the whys and wherefores of the intricate life forces with which he was dealing. In point of fact, it is as natural for Mr. Bur- bank to theorize as it is for him to make practical experiments. His mind is no less incessantly active than his body, and his views on the theories that underlie plant development are as pro- nounced and radical as are his opinions concern- ing practical matters of horticulture and plant management in the fields, regarding which, doubt- less, he has had a larger personal experience than any other man in the world. In briefly outlining Mr. Burbank 's attitude to- ward various of the moot points of heredity, it will be convenient to call attention to a few typical instances of his own experiments that give sup- port to his views. (1) First as to the broad general question of Darwinian evolution. When a very young man Mr. Burbank read with avidity Darwin's then re- [24] A FRUIT-BEARING SLAB OF SPINELESS CACTUS The particular slab here shown is merefy an average specimen. Number- less slabs in the same field bear two or three times as many individual fruits. A slab has been known to bear as many as 150 of these " Cactus pears." THEORIES OF DEVELOPMENT cently issued work, Animals and Plants under Do- mestication, and at once he began making personal scrutiny of all the plants of his neighborhood, and was struck with the fact of universal variation both in the wild state and under cultivation. From the outset, his experiments had to do with selection between individual specimens that differ in some measure from their fellows, and at every stage of his work such a selection continues. "The beginning is selection and the end is selec- tion," declares Mr. Burbank; and the, possibility of developing new races of many types from a single stock through selection alone has been demonstrated by him thousands of times over. As Burbankian selection is after all only nat- ural selection, in which a man's wishes become the chief determining agent among environmental in- fluences, it may fairly be said that the demon- strations made over and over at Santa Eosa have supplied the largest body of evidence for the truth of the doctrine of evolution through natural selec- tion that has anywhere been made available. After studying Mr. Burbank 's results, it is im- possible to doubt that natural selection has been at least one highly important agency in shaping the evolution of the living races. As an instance of the way in which new races may be rapidly developed by artificial selection alone, we may cite the case of the half-dozen new varieties of garden peas, differing radically from one another, and each breeding true to its own kind, that were developed by Mr. Burbank in the [25] LUTHER BURBANK course of six generations from a single parent form. The new variety of heuchera, or "wild gera- nium," with its amazingly corrugated and convo- luted leaf, furnishes another example of extraor- dinary modification of form brought about by merely selecting the seed of an individual that showed a tendency to modification, and carrying on the selection through several successive gen- erations. That the same principle applies equally to the modification of stalk or root or bulb or flower or fruit of plants of every type has been demon- strated so many times over in Mr. Burbank's experience that to cite his proof of the proposition in its entirety would be equivalent to naming all the hundreds of new varieties that he has devel- oped. For the cases are few indeed in which the principle of selection has not been applied at some stage of the experiment. Even where hybridiza- tion has played an important part, it is of course necessary first to select the parents for crossing; and then, in due course, selection is made again among the progeny. So it may be repeated that artificial selection is the keynote to plant development ; and that the experiments at Santa Rosa and Sebastopol fur- nish an unending series of demonstrations as to the way in which nature works in the bringing about of evolution of races through natural selec- tion and the survival of the fittest. (2) As to the question of the transmissibility [26] THEORIES OF DEVELOPMENT of acquired characters, Mr. Burbank answers em- phatically in the affirmative. As he sees the mat- ter, all traits of every species were at some time acquired in response to environmental stimuli. To deny the transmissibility of new traits thus acquired from time to time in the geological ages would be tantamount to denying evolution itself. He finds that plants of closely related species brought from different continents transmit their qualities when interbred; and he has little pa- tience with the modern quibble which would admit the transmissibility of qualities imprinted directly on the germ-plasm, while denying transmissibility of the changes in the body-plasm, in view of the fact that the germ-plasm itself is part of the plant body and, moreover, is apparently disseminated everywhere throughout the plant organism, inas- much as individual buds or pieces of stalk, or bits of root or bulb, may in numberless instances re- produce the entire plant quite as effectively as it is reproduced from the seed. In thus advocating the theory of the universal- ity of acquired traits, however, Mr. Burbank of course does not refer to gross lesions ; and it may be added that he has not personally conducted any experiments in the attempted modification of the germ-plasm through use of chemicals or of radium such as some other workers are now undertaking. [27] LUTHER BURBANK THE OEIGIN OF THE FITTEST (3) As to the origin of the variations observed in nature, which supply the material for the opera- tion of natural selection, Mr. Burbank has very pronounced ideas. He believes that the usual cause of such variation is hybridization between different species or varieties. One of his earliest discoveries was that by crossing divergent races or totally different species he could produce hy- brids that were different from either parent, and that sometimes these hybrids breed true. A striking illustration of this was furnished when he cross-pollenized a raspberry brought from Siberia with a California dewberry — a species of trailing blackberry. The result was a berry of a new type, differing radically from either parent, which seems entitled to rank as a new species, inasmuch as it has its own type. Another illustration of the production of a new species by hybridizing is found in Mr. Burbank 's Phenomenal berry, the product of a union between the Cuthbert raspberry and the California dew- berry. Yet others are the plumcot, already re- ferred to; the extraordinary Paradox walnut, which combines the strains of the Persian walnut and the California black walnut; and the Shasta daisy, combining the strains of a European, an American, and a Japanese species, and itself dif- fering very radically from any one of its an- cestors. Mr. Burbank has found many instances of [28] THEORIES OF DEVELOPMENT hybridization in a state of nature. He has, for example, seen hybrid raspberries growing wild and maintaining their own in the same neighbor- hood with both of their parents. The same thing occurs in the case of a species of madder that grows abundantly along the roadsides near Se- bastopol. Mr. Burbank has seen nuts that he be- lieves to be a natural cross between the pecan and hickory. In a word, he believes that hybridization among wild species is an exceedingly common phe- nomenon, and that this is at least one of the prom- inent means of developing new species and new varieties upon which natural selection may work differentiation of species. Mr. Burbank thus supplements and extends the Darwinian theory, offering what seems the best explanation hitherto suggested of the "origin of the fittest," about which Darwin himself and his chief disciples were very much in the dark. It should be added that Mr. Burbank 's experi- ments, while showing in numberless cases the possibility of the development of new varieties through cross-breeding, show also the limitations that nature puts upon the method by denying fer- tility to hybrids that result from the crossing of parents too widely divergent. For example, he made an extraordinary series of cross-pollenizing experiments in which the strains of many mem- bers of the rose family, including the apple, the pear, the mountain ash, and the rose itself, were blended with those of the blackberry. Similarly he crossed the raspberry and the strawberry, [29] LUTHER BURBANK also the pear and the apple, the pear and the quince, and the quince and the apple; and yet again, the petunia and the tobacco, and the crinum and the amaryllis. But in each of these cases, while very interesting hybrids were produced, they were entirely sterile, and the experiment could go no further. Sometimes species are crossed that are just widely enough divergent so that the offspring are relatively infecund but not actually sterile. Such was the case with the cross between the Persian and the California walnut, the offspring of which is a tree of enormously rapid growth, but bearing only a handful of nuts; whereas another walnut cross, that between the American black walnut of the East and the California black walnut, is enor- mously prolific, bearing bushels of nuts where the other hybrid bears only individual specimens. The celebrated cross between the plum and the apricot furnished interesting illustrations of the same thing. Most of the hybrids thus produced bore imperfect flowers lacking petals or stamens or pistils, as the case might be. It was only after many efforts a specimen was produced that was fertile, yet ultimately the race of hybrid plum- cots was so developed that it now has many varie- ties, some of them being excessively prolific. Yet another instance of the way in which the barriers between species may be broken down by persistent effort (through ultimately finding plants having just the right degree of affinity) is that in which Mr. Burbank produced the sunberry by crossing [30] THEORIES OF DEVELOPMENT two species of solaimm, that he had attempted ineffectually to cross from time to time for twenty-five years, success finally coming in the form of a single fertile seed case. MENDELIAN HEEEDITY (4) As to later progress of hybrid races. Whereas sometimes, in case of the Primus berry, a hybrid shows a combination of the traits of the parents, constituting a new type that breeds true, this is not the usual result of crossing different species or marked varieties. As a rule, the hybrid shows a tendency, as regards any given character, to follow one parent to the exclusion of the other. If, for example, you can cross a stoneless plum with an ordinary plum, you must expect that all the progeny will bear stone fruit. But Mr. Burbank early made the discovery that if hybrid forms are allowed to interbreed, their progeny usually show an extraordinary tendency to variation, some of them reverting in one direc- tion and some in another, and some individuals combining the traits of the two divergent lines of ancestry in new combinations. He discovered that the best opportunity was afforded for the development of new types ; and he eagerly put this discovery to account in numberless breeding ex- periments. Now this discovery, made by Mr. Burbank in the early eighties, is essentially the discovery that had been made twenty years before by Gregor [31] LUTHER BURBANK Mendel, the Austro-Silesian monk, to which no one paid any attention until long afterwards. After Mendel died in 1884, there was an interval of about sixteen years, prior to his rediscovery and the posthumous promulgation of his doctrines by Professor De Vries and others, during which Mr. Burbank was probably the only man in the world who had any clear conception of the essen- tial facts of the segregation and recombination of characters in the second filial generation of cross- bred races. Mr. Burbank did not make mathe- matical tests in connection with his experiments, as Mendel had done ; but he demonstrated the gen- eral truth of what has since come to be known as Mendelian inheritance thousands of times over in the course of his independent experiments at a time when neither he nor anyone else had so much as heard the name of Mendel. It was by application of his independent dis- covery of the principle of the segregation and re- combination of parental characters in the second and subsequent generations that most of his re- markable new varieties and new species were developed. Thus the commercial races of stoneless plums and prunes were produced through blending the strains of a little partially stoneless European plum that was not much bigger than a cranberry, and was acrid and worthless, with the strains of numerous choice varieties of cultivated plums through successive generations, each immediate cross resulting in stone fruit; and the quality of [32] •,:, * MR. BURBANK INSPECTING A CHOICE VARIETY OF SPINELESS CACTUS The picture was taken in the season of 1914. The bed of young spineless cactus plants here shown includes some of the most perfect specimens hitherto developed. They grow in the garden at Santa Rosa. THEORIES OF DEVELOPMENT stonelessness, in combination with other desirable qualities from divergent strains, reappearing only in the subsequent generations. Altogether similar was the history of the thorn- less blackberry, which finally developed into a wonderfully vigorous plant with stems as smooth as pussy-willows, and bearing an abun- dance of luscious fruit, is the product of many generations of cross-breeding through which the quality of thornlessness that was inherent in a little otherwise worthless trailing dewberry from Virginia was combined with the good qualities of sundry varieties of cultivated blackberries that grew on thorn-laden bushes. The development of the white blackberry, from a small variety of brownish- white color to a splen- did berry of snowy whiteness, came about in the same way; and to this day, if you were to cross an ordinary blackberry with the Burbank white variety, you must expect that the progeny will bear black berries, and only in the succeeding generation will plants appear that bear the white fruit of one of their grandparents. SELECTIVE LINE BKEEDING (5) The accentuation of characters by line breeding plays a no less significant part in Mr. Burbank 's scheme of plant development. Whether the plant with which you deal be pure breed of a hybrid, it will seldom happen that a quality that you are attempting to develop is manifested [33] LUTHER BURBANK in superlative degree. It may be, indeed, that the desired quality appears only as a faint trace or suggestion. Such was the case, for example, with a certain specimen of the calla in which Mr. Burbank de- tected a faint trace of a pleasant perfume. He carefully preserved the seeds of that calla, and by similarly selecting among the descendants he produced a race of perfumed callas. In the same way he produced scented petunias and verbenas that have gained great popularity. Again, Mr. Burbank once found a specimen of the California poppy that had a faint line of red extending down one of its golden petals. This specimen was transplanted and treasured. Among its progeny was a specimen that showed a slightly more conspicuous red line on a petal of one of its flowers. The seed of this specimen was pre- served ; and so on generation after generation, the tendency to red being accentuated in a few indi- viduals in each generation; until finally a new variety of poppy had been produced in which the normal golden color had disappeared altogether, and the entire flower was of a bright crimson — justifying the name of "Fireflame" that was given it. The Santa Rosa Shirley poppy, with its deli- cately crenated petals; the silver-lining poppy, with the inner surface of its petals transformed from red to white, and the wonderful blue poppy, selected out, through generations of breeding, as the remote descendant of an individual red poppy [34] THEORIES OF DEVELOPMENT whose petals showed a trace of cloudiness, are other striking examples of the accentuation of a character through line breeding. The sturdy winter rhubarb has been developed in the same way from the plant imported from New Zealand with a stem no larger than a pencil. The absolutely smooth cactus is the descendant of plants that only showed a tendency to be some- what less spiny than their fellows. CREATION OR RECRUDESCENCE An interesting question arises as to whether such accentuation of a peculiarity or tendency may amount to the bringing out of a new char- acter that was not represented in any ancestor, near or remote. Is Mr. Burbank's light blue poppy, for example, the first of its kind; or were there blue flowers among some of the ancestors of the poppy? The best view appears to be that the seemingly new trait was really submerged in the ancestral germ-plasm, if the phrase be allowed, and has been made tangible by the removal of more or less antagonistic traits that obscured it. In the case of the blue poppy, for example, the sub- mergence was doubtless of long duration, for blue poppies have not been in fashion within the mem- ory of man; but through successive generations of selection the factors for redness and yellow- ness were removed, and an individual finally pro- duced in which the primal blue, which was prob- [35] LUTHER BURBANK ably the color of some very remote ancestral poppy, was revealed. In a crude general way, the process might be compared to the restoration of an ancient canvas by the removal of successive layers of pigment with which it has been overlaid. THE COLORS OF FLOWERS EXPLAINED While the colors of flowers are under consid- eration, it may be well to say a word about a theory as to flower coloration that may sometimes prove helpful in carrying out a line of experi- ments; the theory, namely, that all flowers were originally green and that as evolution progressed they varied up and down the chromatic scale, — some lines of descent producing successive blue and indigo and violet flowers, while other lines of descent produced yellow and orange and red flowers instead. If we hold that hereditary factors once acquired by any race are never altogether lost from the germ-plasm of that race, it would follow that all red flowers have the potentialities of orange and yellow in their heredity, and that all violet flowers have the potentialities of indigo and blue. Moreover, since there would have been cross- breeding at all stages of development, it may fairly be assumed that there are strains of blue as well as of orange and yellow in the red flower ; also strains of blue in the yellow flower, and strains of yellow in the red flower. There is some evidence to show that white flow- [36] THEORIES OF DEVELOPMENT ers may be due to a blending of pigments — say a mixture of yellow and blue. White may also be due to a prismatic effect induced by the presence of air spaces between the cells. It is fairly .clear that different colors may be advantageous for the flower according to the mode of growth of the plant on which the flower is borne. Thus plants that grow in the shadow and those that bloom in the evening advan- tageously bear white or pale yellow flowers, as these are more conspicuous than the most gaudily hued flower would be under the circumstances. On the other hand, a plant that grows in the open may bear a red flower both because that color will be attractive to insects that fertilize the flower and because the reflection of the long waves of light (giving our eye the impression of red) serves to shield the petals from excessive heat. If, then, most flowers have the potentialities of wide color variation, there is opportunity for the play of natural selection in adapting each flower to the environment in which the plant on which it grows flourishes to best advantage. This theory of flower coloration finds a measure of support in another theory which attempts to explain the peculiar phenomena of " dominance ' ' and "recessiveness" as manifested in Mendelian heredity. According to this explanation, where two antagonistic characters thus Mendelize, the one that is dominant is the newer character and the one that is recessive is the older. This pre- cisely reverses the view that has been suggested [37] LUTHER BURBANK by some biologists, but there is a large amount of evidence to support it. To illustrate from the case in point, it appears that, as a rule, when red flowers are crossed with flowers of another color, say white, the red tends to prove dominant. Similarly, when a white poppy is crossed with Mr. Burbank's blue one, the progeny are white. This is consistent, at least, with the theoretical assumption that new characters dominate old ones, and that red is the newest flower color and white a newer color than blue. I must not claim space to elucidate either theory in detail here. But I may point out, in passing, that the theory that new strains are dominant to older ones aids us sometimes in the interpretation of the observed results of experiments in plant breeding. We should expect, for example, that the spines would be dominant to spinelessness in ease of the blackberry and cactus, for it may be assumed that the spines were a comparatively recent development in the evolutionary scale. Again, pigment would be dominant to lack of pig- ment in the blackberry; for the fact that the young berries are colorless or green strongly sup- ports the assumption that the primordial an- cestors of the blackberry bore colorless fruit. FIXING CHAEACTEKS In a slightly different connection it may be noted that study of dominance and recessiveness [38] THEORIES OF DEVELOPMENT in plant characters is of the utmost practical im- portance for the plant developer as an aid in fix- ing characters so that they will breed true, often a task of great difficulty. This does not matter, of course, in the case of orchard fruits, which are propagated by grafting, and of various bulbous and other plants that are propagated by root division. But in case of an- nuals grown from the seed it is highly important that a new desirable character should be fixed in such a way that it will be reproduced in the progeny. Now according to the Mendelian formula, in its simplest terms, where any pair of antagonistic characters that Mendelize are in question, the re- cessive character which disappears absolutely in the first filial generation will reappear tangibly in one in four of the offspring of the second gen- eration, and will be submerged in the germ-plasm of two others of each group of four, the remaining member of the group being a pure dominant. To illustrate from Mendel's careful experi- ments, when a tall and a short variety of garden pea are crossed, all the progeny are tall; but in the next generation one specimen in four is short and the other two specimens, while individually tall, have the factors for shortness submerged in their germ-plasm. The short specimen being purely recessive will breed true to shortness ; but the two tall specimens that are mixed will not breed true. The same principle holds for any pair of an- [39] LUTHER BURBANK tagonistic characters that show the phenomena of dominance and recessiveness. It follows that if a character which you are striving to fix in any given experiment is a re- cessive character, it is fixed from the moment when it reappears and you may give yourself no further concern in the matter. But if it be a dominant character, then you must be on the look- out, since of every three specimens that show the character, two will have factors for the antag- onistic character in their germ-plasm, and do not constitute fixed strains. Only by watching through another generation can it be determined which individuals are "pure dominants," and such alone will breed true. Until the Mendelian formula was known breed- ers were often put to their wits' end to segregate a strain that would breed true ; whereas now, with the formula in mind, this may usually be accom- plished in two generations. 'S LOOKING FORWARD In the preceding pages a few of the general principles of plant development have been out- lined, by way of a preliminary sketch of Mr. Bur- bank's methods. In the chapters that follow these methods will be illustrated at greater length and in much fuller detail. It seemed well, however, to prepare the reader with this preliminary outline for the detailed studies that are to follow. In the immediately succeeding chapters, we [40] THEORIES OF DEVELOPMENT shall take up the practical aspects of Mr. Bur- bank's work, in effect going with him into the fields and observing the carrying out of the prac- tical work of the horticulturist. It will be con- venient first to examine his method of caring for seeds and the nature and development of seed- lings. Then in successive chapters we shall go with him into the orchard, the small-fruit garden, the vegetable and flower gardens, and the lawn and dooryard, gaming characteristic glimpses of his manifold activities. It is obvious that with the space at command it would be impossible to name each and every one of the plants with which Mr. Burbank has experi- mented effectively. At best we can mention only the more typical or the more spectacular cases. But I would again remind the reader that a very complete exposition of his entire lifework has been given by Mr. Burbank himself in a series of volumes, twelve in number, illustrated by no fewer that twelve hundred and sixty beautiful color plates. To this work the reader who wishes a more extensive presentation of the work of plant development as carried out by the Santa Eosa ex- perimenter may turn with full confidence and with pleasurable anticipations. Meantime it may not be amiss to repeat that the present book, although necessarily condensed in its treatment, endeavors to give the essentials of Mr. Burbank 's methods and results, and that the illustrations of Mr. Burbank 's work here pre- sented are drawn from a first-hand study of his [41] LUTHER BUKBANK activities at Santa Eosa and Sebastopol, and the fullest examination of the original manuscripts and records made accessible to the writer in his capacity of editor-in-chief of Mr. Burbank's works. [42] PART II WITH LUTHEE BURBANK IN ORCHARD, GARDEN, FIELD, AND FOREST CHAPTER III THE CARE OF SEEDS AND SEEDLINGS IT will give new zest to your work in the gar- den to feel that you are producing new varie- ties of vegetables or fruit or flowers not only different from those of your neighbors, but dif- ferent from anything that ever existed before. It would have seemed paradoxical a few years ago to suggest such creative possibilities, but Mr. Bur- bank has shown the way, and the succeeding chap- ters will relate his methods clearly and explicitly. In broad general terms, it may be said that the Burbank method consists of (1) the selection of desired traits and their accentuation through suc- cessive generations, combined with (2) artificial hybridization through which variation is stimu- lated, and through which different racial strains are brought together to produce unique combina- tions. The precise way in which such selective breed- ing is carried out will be specifically detailed in connection with our studies of work in the orchard, the small-fruit garden, the vegetable gar- den, the flower garden, and on the lawn. But as preliminary to such studies, it will be well to learn just how Mr. Burbank prepares the soil and carries out the tedious but necessary [45] LUTHER BURBANK steps of seed planting and the nurture of seed- lings, which are substantially the same for all types of vegetables, and which are among the most essential of the processes of practical gardening. CHOICE AND CAEE OF SEEDS It is obvious that no success could attend the effort at plant development unless seeds are prop- erly chosen and properly cared for. After experi- ments are under way, you will of course gather seeds from your own plants, but at the beginning of your experiments you must secure seeds from some other source. Mr. Burbank especially cau- tions you to procure your supplies from some reputable seedsman, so that you may have fair assurance that you are making a good beginning. It is obviously foolish to begin with poor varieties, when you might with equal ease have good varie- ties from which to select. Study seed catalogues, then, and decide on a certain number of species with which you wish to experiment, and secure seeds of the best available varieties of the species. Mr. Burbank himself regards the care of seeds as among the very most important phases of his work. The seeds of his choicest varieties are kept over winter in boxes in a room of his own dwell- ing, where they are directly under his eye, and the method of dealing with these seeds in the early springtime is one to which he has given a vast deal of attention, and regarding which he has per- fected a plan that insures the best possible results. [46] SEEDS AND SEEDLINGS Fortunately, the method of sprouting seeds is practically the same for the most diverse kinds. Mr. Burbank has seeds sent him from all parts of the world. He applies the same method of germi- nation to them all, and he has so perfected the method that he confidently expects to secure at least ninety-nine seedlings from every hundred seeds of whatever kind. The importance of being able to germinate seeds of rare exotics with some such degree of certainty is obvious. It is no less important to make sure of the germination of seeds produced by difficult hybridizing experiments. For example, Mr. Bur- bank worked for twenty-five years unsuccessfully in attempting to hybridize two species of night- shade, and finally he produced a single berry. The solicitude with which he guarded the seeds of that berry may well be imagined. From one of those seeds sprang the plant that became the progenitor of the entire race of sunberries. And this is only one instance of many in which all the potentialities of a new race of fruits or flowers or vegetables were represented in a little cluster of seeds that by the slightest mismanage- ment might be destroyed, thus bringing to naught a long series of experiments. Bearing this in mind, we shall not wonder that Mr. Burbank keeps his unique collection of seeds constantly under his own eye, or that he person- ally supervises the planting of these seeds in the early springtime. [47] LUTHER BURBANK PKEPABING THE SOIL It is Mr. Burbank's unvarying custom to plant all important seeds in boxes that at first are kept in the greenhouse, so that the seedlings may get an early start, and for a time be protected from the elements. For many years he has used boxes of a uniform size and type, and such boxes he considers far better than pots or earthen pans. The boxes he uses are eighteen inches square, outside measure, and four and one-half inches deep, inside measure. He prefers redwood lumber, but where this cannot be obtained cypress will answer nearly as well. Chestnut wood is also very durable, and locust is even more so. Soft pine should be avoided. Two opposite sides of the box are boards three- quarters or seven-eighths of an inch thick, the other sides are a little less than half an inch thick. The bottom of the box is made of lumber about one-quarter of an inch thick, two or more spaces of an eighth of an inch being left for drainage. Across the bottoms are nailed three strips to add rigidity and strength, and to afford better ventila- tion and drainage. It is well to dip the joints in linseed oil before they are nailed together. This gives durability and tends to prevent the nails from rusting. Such a box as this, if sterilized once a year by being placed for three or four minutes in boiling water, may be used for many years. In preparing the soil to fill the boxes, Mr. Bur- [48] SEEDS AND SEEDLINGS bank uses about one-half clean, rather coarse, sharp sand, and about forty per cent of good pasture or forest soil, preferably that containing more or less leaf mold. To this it is desirable to add from five to ten per cent finely powdered moss or peat. These ingredients are intimately mixed, with the addition of about one or two per cent of fine-ground bone meal or superphosphate, obtain- able from any dealer in gardener's supplies. This mixture makes a soil in which seeds of almost any kind of plant from any part of the world will germinate, and in which the seedlings will thrive until they are ready for transplanting. Mr. Burbank recommends that soil of this kind, after being once used, shall not be thrown away, but shall be retained for mixture with new soil prepared in a succeeding season. He always keeps a little of the old soil on hand for this purpose. If very choice seeds are to be grown, the soil, new or old, is sterilized by thorough scalding to destroy bacterial or fungus or insect pests. Before filling the boxes with soil, it is well to scatter coarse gravel over the bottom to a depth of from one-quarter to a half inch. Use gravel that will just pass through a half -inch mesh, or a little smaller. This insures perfect drainage and sufficient aeration, both of which are of the utmost importance. Then fill the box with the prepared soil to within about an inch of the top. When cool damp weather is to be expected, and [49] LUTHER BURBANK slow growth, make the filling somewhat shallower to prevent drowning or "damping off" of the seedlings. For spring planting make the earth a little deeper to prevent too sudden drying out, and otherwise to regulate the amount of moisture. PLANTING THE SEEDS Having filled the box with the prepared soil to the right depth, level the surface of the soil by pressing it down with a flat piece of board until it is smooth and fairly solid. Then sow the seeds quite thickly on this smooth surface, and dust a handful of the prepared soil over them. In the case of very small seeds, a mere sprinkling of the soil is enough. For larger seeds sprinkle the soil to a depth of one-eighth or one-quarter of an inch. A very common mistake is to cover the seeds too deeply. It should be recalled that the tender sprout must force its way upward against the weight of soil that covers it. The soil covering should be sufficient to give it protection, but not enough to be burdensome. If too deeply covered, tender seedlings may not be able to force their way to the surface. When seeds are planted in fields, and it is neces- sary to give them protection from the weather, Mr. Burbank entirely covers them with a thin layer of earth and sprinkles over this a layer of sawdust which will serve the purpose of equaliz- ing the temperature, and will not subject the sprouting plant to undue weight. Even in the [50] SEEDS AXD SEEDLINGS case of seeds planted in boxes the sawdust may be used, but in most cases powdered moss may be employed to better advantage. A thin layer of moss sifted over the seeds acts as a non-conductive blanket, equalizing the tem- perature and retaining moisture. A very thin layer of gravel or coarse sand may be sprinkled over the moss to hold it in place. This layer of gravel not only prevents the young plants from being washed about, but also serves as a barrier against the spread of fungous growths should they subsequently attack any of the seedlings. After the seeds are planted and covered in the way just described, they should be watered not by sprinkling the surface, but by placing the boxes into a tub containing water of sufficient depth to rise nearly or quite to the surface of the soil. Thus in a few minutes the water saturates the entire contents of the box without disturbing the seed or packing the soil. The boxes are then removed and tilted to one side so that the super- fluous water can drain out. Mr. Burbank urges that every detail of this process of soil preparation and seed planting is of vital importance. By strict attention to details, success is virtually assured. CABE OF THE SEEDLINGS Of course the seed boxes should be kept at mod- erate temperature, in a fairly warm room, or in [51] LUTHER BURBANK the greenhouse until the season is far enough ad- vanced for outdoor transplanting. If the season is delayed, it will be well to trans- plant the seedlings from the original box into another one similarly prepared, in order that they may have room to develop. In the case of small plants like the calceo- larias, lobelias, begonias, ferns, and the like, the little plantlets may be transplanted, as soon as they are visible, by lifting them on the end of a moistened quill, pencil, or small knife blade, and placing them in a box that has been previously moistened, then covering them with glass for a few days. If the seedlings are not transplanted at this early stage, removal should not be deferred be- yond the time when the little plants have from two to four leaves. Transplanting at this stage is a very simple process, effected with quill or knife blade. The seedlings should be placed in straight rows in new boxes, from six to twelve rows in a box, according to the size of the plants. After remaining in the greenhouse for a week or two, the boxes of seedlings are removed to a sheltered place out of doors, in order that they may become hardened through exposure to sun- shine and outdoor air. If the season is backward, it may be desirable to transplant the seedlings a second time into other boxes, to give them more room. But if the season is sufficiently advanced they may be transferred directly to the garden. Mr. Burbank especially cautions against mak- [52] SEEDS AND SEEDLINGS ing too sudden a transfer from greenhouse to field. It is well to accustom the seedlings to out- of-door conditions by placing the boxes at first in propagating beds, surrounded by high boards, and covered with frames made of laths nailed on narrow strips of board in such a way that the spaces between the laths are about equal to the width of a single lath. These frames give partial protection from sun and wind and prepare the seedlings for open-air conditions. In making the final transplantation, it is well to take the boxes to the field so that each plant is transferred with the least possible exposure. In California tender plants best withstand mov- ing from the greenhouse to the open air just be- fore or during a warm rain, the atmospheric con- ditions at this time being similar to those of a greenhouse. The final transplanting is done with a trowel, taking up enough dirt to include all the roots. Mark the rows with a guard line, and make a long narrow crevice by inserting a flat spade and moving the handle back and forth gently. Be sure that the crevice is deep enough to take in the roots of the plant fully extended. Plant the seed- ling a little deeper than it grew in the box, and draw the soil about it and pack it quite firmly against the roots. Use the common garden rake in leveling and loosening up the soil along each side of the row to prevent " baking," and to keep the temperature equable and the soil moist. [53] LUTHER BURBANK The tender seedlings may be destroyed by a cold dry wind, or by too much moisture and too little air. They should be protected for a day or two if a dry wind comes up, and the soil about them should not be soaked with water, although kept in a moist condition. RUNNING THE GAUNTLET There are numerous fungoid and insect pests that threaten the seedling during its infancy. Little patches of fungus may appear in a box of seedlings, and this may spread rapidly until the entire company is destroyed. A sprinkling of sulphur over the plants, or of coarse dry sand or gravel about their roots, may prevent the fungus from spreading. It will be well to place the box in a cold dry atmosphere so that the excessive moisture is evaporated. The fungus pests are most likely to attack the seed- lings if they have been kept in too close and damp an atmosphere. After the plants are in the field they should quickly develop a hardiness that makes them im- mune to the attacks of fungoid pests. Mr. Bur- bank has all along made a very particular point of the development of hardy races of plants. He at once removes and destroys any seedlings that show susceptibility to the fungus or bacterial pests. In this way he develops races that are immune, and he never finds it necessary to use germicidal sprays in his orchards and gardens. [54] SEEDS AND SEEDLINGS To a certain extent plants may be developed that are resistant also to the attacks of insect pests. But it is necessary to guard the tender seedlings against the attacks of these enemies. One should be on the lookout from the outset for the various cohorts of insects, slugs, cutworms, eel-worms, crickets, and aphides that feast on tender tissues of seedlings. Slugs may sometimes be headed off by sprin- kling lime, red pepper, quassia, or tobacco dust in their path. The pests known as the thrips and the aphides are best destroyed by fumigating the greenhouse once or twice a month with tobacco smoke. In general a careful watch should be kept for the pests, and the seedlings mechanically guarded against them so far as possible. The proper sterilization of the soil at the outset will save a vast deal of trouble at a later stage. The description just given outlines the method that Mr. Burbank applies to the seeds that come to him from all parts of the world and to those raised on his own grounds. The rules just given for the planting of seeds and the early care of seedlings apply to plants of every description. Whatever the varieties with which you intend to experiment, — flowers, vege- tables, small fruits, orchard fruits, or forest trees, — the initial steps are the same. [55] CHAPTER IV WITH BURBANK IN THE ORCHARD AjMOST every country dooryard has one or two orchard trees in some odd corner, — an apple or pear tree, or cherry or plum. For the most part these trees bear indifferent fruit, and it does not occur to their owners that they could be improved. Yet in point of fact it would be an easy matter to graft scions or buds of good stock on these trees, and produce fruits of the finest varieties, instead of inferior ones. You may have a hundred or more different varieties on a single tree if you like. Mr. Bur- bank sometimes has a thousand. Moreover, it would be quite feasible to make the old tree the seat of experiments in the devel- opment of new kinds of fruit — absolutely new kinds, such as no one ever saw before. That is what Mr. Burbank would do with the tree. He would seek its co-operation at once ; do some pol- lenizing and grafting; and pretty soon the old, "worthless" tree would be the most interesting and important tree in that part of the world. The ensuing pages will tell just how he would go about it — and how you may imitate his methods. [56] BURBANK IN THE ORCHARD OEEATING NEW SPECIES Mr. Bui-bank early discovered that by hybridiz- ing different species of plants he could produce new varieties — even new species. At the time when this discovery was made most botanists and horticulturists supposed that a cross between two species would be infertile. Mr. Bur- bank proved that, quite to the contrary, some hybrids show an extraordinary degree of fecund- ity. Everything depends upon the degree of re- lationship of the parent forms. Species that are too widely separated do not interbreed. Those that are a little less widely separated may pro- duce sterile offspring, — mules. Where the rela- tionship is still closer, the hybrid offspring may not be sterile, and yet may be less productive than either parent. But where the degree of affinity is just right, the offspring may show a vigor and fecundity far in excess of that of either parent. The hybridizing of more or less closely related species and varieties of plants, then, constitutes a fundamental part of Mr. Burbank's procedure in the creation of new forms. He has hybridized about two hundred different species. Among the orchard fruits thus crossed are the plum and the apricot (producing the wonderful plumcot), apple and pear, apple and quince, quince and pear, peach and nectarine, peach and almond, and orange and lemon. Strange and interesting forms have resulted [57] LUTHER BURBANK from some of these crosses, — a smooth-skinned peach that bears an edible almond seed at its heart, to name a single example. Crosses between different varieties within a species have been made by thousands, producing hundreds of new varieties of plums, prunes, peaches, apples, pears, cherries, and quinces. Stoneless plums and prunes ; plums that look like apples and taste like them; gigantic red-cheeked pears; cherries for canning that leave the stone on the tree when you pick them; colossal, savory quinces, borne on mere bushes — these are some of the results, named almost at random. Hybridizing experiments that hold out such possibilities are worth trying. We shall see how to go about them in a moment. Another fundamental method, supplementing the method of hybridization, is that of selection among varying individuals of the same species or variety. No two individuals are just alike, from which it follows that in a given company of plants of the same kind there are various grada- tions as to size and shape of leaf, form and color of flower, or flavor of fruit ; and, as regards each varying quality, there must obviously be one in- dividual, if you will carefully search it out, that exhibits this quality most markedly. Or there may be an individual that shows just a trace of a new quality — say a unique flavor or color. This is the individual to select for further breeding experiments, in expectation of accentu- ating the quality in question. For instance, Mr. Burbank found a cherry that [58] BURBANK IN THE ORCHARD tended to fruit early: its descendant is the Early Burbank, which ripens three weeks before any other cherry. He found a hybrid prune that was a trifle sweeter than its fellows : its descendant is the Burbank sugar prune, with its twenty-three per cent sugar content. He found a quince with slightly modified texture and flavor: its descend- ant is the pineapple quince, gigantic in size, good to eat raw like an apple, and with the flavor of a pineapple. Any quality that can be detected at all can almost surely be accentuated by selective breeding. SEEDS AND SEEDLINGS In experimenting with a plant, Mr. Burbank has, of course, a clear idea of the modification he wishes to produce. As a rule, a number of quali- ties— often a dozen or more — are under considera- tion at the same time. If the fruit is a cherry, for example, it will perhaps be desirable to enlarge the fruit, make it sweeter, redder, and juicier; improve its keeping quality; decrease the size of the stone, and shorten the stem; while at the same time making the tree a hardy, regular, and prolific bearer, with the fixed habit of ripening its fruit very early in the season. To get such a combination, the right heredities must be blended, as a matter of course. But there will be extraordinary diversities in the same fra- ternity; and the chance of securing a plant that shows any given combination of qualities in super- [59] LUTHER BURBANK lative degree increases in direct proportion with the number of seedlings from which selection can be made. Hence one of Mr. Burbank 's hobbies is the pro- duction of seedlings in great quantity. This is not so essential in hybrid seedlings in the first generation, but it is highly important in the second generation, because then the plants begin to show a very wide range of variation — f or reasons that we shall examine in another connection. So Mr. Burbank saves all the seeds of a plant that attracts his attention, and sows them in a carefully prepared soil in greenhouse boxes. De- tails as to his method have already been given. We may add that the same method is used for seeds of practically every variety, — rare exotics of many kinds and the commonest garden plant; seed of the spineless cactus or that of orchard fruit. Whatever the variety, Mr. Burbank nur- tures and transplants the tiny seedlings, giving each one of them a chance to show its quality in open competition. RUNNING THE GAUNTLET The tiny seedlings of the plum or the cherry or apple or pear or quince are transplanted into a field pretty close together, for economy of space, and are carefully weeded and cultivated until they attain an average growth of about one foot. Then Mr. Burbank subjects them to a rigid in- spection. He passes along the row, and gives a [60] BURBANK IN THE ORCHARD quick but searching glance at each successive seedling. He knows precisely what he is looking for, and his eye detects niceties of variation that would be discerned by no one else. Mr. Burbank is able thus to pass under review, for appraisal, five thousand, ten thousand, even twenty thousand seedlings in an hour. This ca- pacity for almost occult divination of the qualities of the seedling enables him to make thousands of series of experiments simultaneously, and to test millions of plants on experiment farms that have an aggregate surface of only twenty-two acres. He is always carrying forward at least three thou- sand series of experiments. All in all, he has car- ried out more than one hundred thousand such series of experiments, involving almost as many varieties of plants (for he seldom repeats an ex- periment), and more than three thousand distinct species. It will be understood, of course, that the experi- ment is not finished when the seedlings are se- lected. It is really only begun. The selected seed- ling must be grafted, and allowed in due course to bear fruit. Then, and not before, can its quality be finally and positively known. Visitors who have seen Mr. Burbank making such a test as that just suggested have sometimes questioned whether it could possibly be a really accurate one. The results achieved should fairly enough an- swer the question, but the matter has been put to an even more decisive test. On one occasion, [61] LUTHER BURBANK Mr. Burbank was selecting among thousands of plum seedlings, directing his assistants to uproot them and deposit them in three piles, — a very small pile for those that he deemed excellent, a medium-sized pile for the fairly good ones, and a large pile for those that were regarded as worth- less. An amateur horticulturist who watched him de- clared that he was making the selection much too rapidly, and that he could not possibly forecast the possibilities of the seedling with certainty. Mr. Burbank suggested that he put the matter to a test. Accordingly a bunch of seedlings was taken from each pile, and grafted on three plum trees of similar size and character that stood side by side. Of course it was necessary to wait two or three years to learn the result. But when the grafted scions were old enough to bear fruit, the accuracy of Mr. Burbank 's prevision was fully proved. The scions from the rejected lot bore no fruit of value. Those from the medium lot bore some fairly good fruit, but not one that produced a variety of exceptional value. Meantime the tree bearing the scions that were originally selected as "best" bore such a pro- fusion of excellent fruit, of twenty-three different new varieties, that the amateur who had sug- gested the experiment named it the Klondike, de- claring that he had never before seen so much good fruit on a single tree. [62] BURBANK IN THE ORCHARD HOW TO SELECT SEEDLINGS This capacity to judge the possibilities of a future tree by merely glancing at the seedling is doubtless in part a matter of intuition. It has been said of Mr. Burbank, perhaps with- out much exaggeration, that he has the keenest senses of any man in the world. But of course a profound knowledge, based on a lifetime of study, supplements and checks direct observation, and something of this knowledge can be conveyed to others. Doubtless no one else can hope to select seed- lings with quite the certainty of the master, yet everyone can learn at least a few general char- acteristics that should be looked for in the seed- ling of a future fruit tree. Mr. Burbank tells us that the desirable qualities include relative thickness and sturdiness of stock and branches, round "fat" buds, and large thick leaves of deep rich color. Vigor of growth is also important, this being an inherent trait that is manifested by the seedling from the moment that it breaks through the soil. A tendency to upright growth is also desirable. A seedling that shows these qualities, and that has the general appear- ance of health and entire freedom from fungous growths, may safely be looked to as a future pro- ducer of fruit of good quality. On the other hand, a seedling that lacks vigor, is of slender stock and; branch, with thin buds and leaves of poor shape or faded color, should be [63] LUTHER BURBANK rejected. And in particular, any seedling that is attacked by mildew or other fungous growths, whatever its other qualities, should be at once up- rooted. Immunity to disease is a sine qua non. The quality that gives immunity is inherent in the germ-plasm of the individual, and a susceptible seedling will make a susceptible tree. Mr. Burbank's trees do not need to be sprayed to protect them against bacterial and fungous dis- eases, because they are raised from immune stock. In developing an orchard you will do well to follow the same rule rigidly, even though it leads you to destroy seedlings that otherwise appeared to be the best in an entire lot. HUKRYING THE SEEDLINGS BY GRAFTING Of course the seedlings that are selected for preservation might be transplanted and left to develop on their own roots. But this would be much too slow a process to meet the needs of Mr. Burbank's experiments. He knows that as a rule he must carry the experi- ment through several generations before he has developed the choice new variety of fruit that he has in mind. That is to say, he must await the flowering of his seedlings; cross-fertilize them; save the seeds of their fruit, plant them, and raise another crop of seedlings ; which in turn will be submitted to the same process of selection, grafting, and cross- fertilization. The object is to breed into the com- [64] MR. BTJRBANK INSPECTING CROSS-BRED TOMATO SEEDLINGS The specimens depicted were altogether extraordinary, in that the cotyledons shown when they first issued from the ground were not smooth, as is almost invariable with every species of plants, but deeply serrated. In all Mr. Bin-bank's experiments, involving inspection of millions on millions of seedlings, he has never observed this phenomenon before. These specimens appeared in the season of 1914. BURBANK IN THE ORCHARD plex hybrid the diverse traits of different species. Of course only two species can be blended in a single cross, so repeated crossings will be necessary. Obviously, then, it is desirable to shorten as much as possible the interval between generations. And Mr. Burbank has learned that the way in which this may best be accomplished is by cutting the seedling from its own roots, and grafting it as a scion on the branch of a mature tree. He has discovered that if the graft is placed on the trunk of a tree or on a large branch, it will develop less rapidly than if placed on a twig near the end of a branch. So he grafts his seedlings in this way when they are very small, putting them on branches that are usually not more than half an inch in diameter. Thus placed, the scions usually bear fruit in the second year (exception- ally, even in the first), whereas if they had been left to grow on their own roots they might not have borne until the fifth or sixth year. Thus an experiment may be carried through four or five generations in the time that would otherwise be required for two generations. By the adoption of such time-saving methods, Mr. Burbank has been able to crowd the work of sev- eral human generations into a single lifetime. There are several methods of grafting, but the essential principle with all of them is merely that the inner or living layer of the bark — called the cambium layer — of the stock and scion shall be brought in contact, not necessarily throughout its [65] LUTHER BURBANK extent, but at least in one place. If a scion is to be grafted on a branch of its own size, or not very much larger, each is cut across obliquely, and each is slit or notched, so that when pressed together they interlock, the scion thus being held pretty firmly. Such a graft is called a "whip" graft or "splice" graft. A scion may be engrafted on the trunk of a sapling by bending the sapling and making an oblique incision with a knife, into which the wedge-shaped scion is inserted, care being taken, of course, that the living tissues come in contact. This is called a "side" graft. The same method may be employed to graft a scion on the root of a tree. Where the graft is planted on a larger limb, the method of "cleft" grafting is employed. This consists of sawing off the branch of the stock, and splitting it with a knife or wedge at the end. The base of the scion is cut into a wedge shape, and this is thrust into the cleft in such a way that the inner bark of the scion comes in con- tact with that of the stock. A scion may be in- serted on either side of the stock, or in the case of a large branch four or more scions may be placed on the same branch. The process of grafting is completed by cover- ing the exposed surfaces with grafting-wax, and wrapping a cloth about the branch for further protection during the time of healing. Mr. Bur- bank's formula for grafting- wax is as follows: "Eight pounds of resin and one pound of bees- [66] BURBANK IN THE ORCHARD wax or paraffin (either will do if no acid or alkali is present, though beeswax is generally preferred) are mixed with one and one-half pounds of raw linseed oil. Boiled oil should be avoided, as it often contains chemicals injurious to plant life. If the wax is to be used in cold weather, it is better to use only seven and one-half pounds of resin and a half-pound of beeswax in the mixture, thus giving a slightly thinner consistency." The ingredients are slowly heated together until melted and thoroughly combined. When partly cool, the composition is poured into pressed tin pans, from which the cakes may be removed when needed by turning the pan upside down and pouring boiling water over it for a few seconds. For use, the wax is heated, preferably in a double heater, the outer one containing water, to prevent overheating. It is applied with a small paint- brush, first around the thick bark of the stock, and later, as the wax on the brush cools, on and about the cut surfaces and open joints. THE PEOCESS OF BUDDING When Mr. Burbank has to deal with a very rare seedling, or one that he wishes to multiply rapidly, he uses the modified form of grafting known as budding. The process consists in slicing off a well-ripened bud, including a piece of bark about an inch and a half long, the incision being just deep enough to include the cambium layer and a small portion [67] LUTHER BURBANK of wood. A T-shaped incision is made in the bark of the tree that is to serve as host ; the upper corners of the vertical slit are gently lifted with a knife and turned back to reveal the cambium layer ; and the bud is slipped into the little pocket thus formed, and the flaps of bark are brought over it and securely tied. No wax is required. The binding cord must be removed in from ten to fourteen days, in order not to constrict the branch. Ordinary grafting, as described above, may best be performed rather early in the spring, or just as the buds are starting. But budding is usually done in June, July, or August, while the trees are in full leaf and vigorous growth. Per- haps the best time is just before the end of the most rapid-growing season in the early summer. If transplanted late in summer, the bud usually remains dormant until the following spring. If budding is done in June, the branch should be broken over a short distance above the bud, but not at first wholly removed, to keep up a partial circulation. The bud may then start growing almost immediately. These are called June buds by nurserymen. A branch from three to six feet in length may grow from a bud in a single season. If you have young seedlings with vigorous roots, they may be grafted or budded with choice varieties, and in many cases a better tree will be secured than if it grew on its own roots. It will be understood, however, that scions must be [68] BURBANK IN THE ORCHARD grafted on trees of kindred species. You cannot graft a stone fruit, for example, on a seed fruit, or vice versa. But a cultivated apple may thrive when grafted on roots of the wild crab apple. Pear scions do well on wild or inferior varieties of pears. Cultivated varieties of plums may be grafted on hardy and vigorous wild plums. Apricot scions thrive on seedling plum or peach stock. One of Mr. Burbank's striking feats in his early experience in California, while he was carrying on the business of a nurseryman, was to establish an orchard of twenty thousand prunes in a single season by raising almonds from seed (sprouting them between layers of gunnysack covered with moist sand), and grafting prune scions on them as soon as they were large enough. Mr. Burbank habitually tests scores or even hundreds of new varieties on a single tree. On his Gold Ridge Farm at Sebastopol there are single acres on which ripen several thousand dis- tinct varieties of hybrid seedling plums that, if tested each on a separate tree, would require, it is estimated, something like seven hundred acres of land. It is obvious, then, that if you have on your grounds an apple tree or two, a plum, a pear, and a cherry, even if they are all of inferior varie- ties, you may quickly establish colonies of all the common orchard fruits, in the choicest varieties, by grafting or budding with scions that may be secured from any good nursery. [69] LUTHER BURBANK Under the circumstances, it is your own fault if your trees do not produce good fruit. SEEKING NEW VAEIETIES An added advantage that Mr. Burbank gains by having many varieties of an orchard fruit growing on a single tree is that the process of hybridizing, through which, as we have seen, new varieties are developed, is thus facilitated. This process consists primarily in fertilizing the flower of one variety with pollen from another. The process is a simple one, particularly in the case of the orchard fruits. Its results are sometimes very remarkable, but of course they are not im- mediately manifest. If you examine the flower of apple or plum or cherry, you will see that it bears a cluster of stamens grouped about the central pistil. Each stamen has at its end an anther that when mature bursts open and reveals a quantity of pollen. Under natural conditions the pollen is trans- ferred from one flower to another through the agency of bees, and natural hybrids are not in- frequently thus produced. All that is necessary to produce cross-fertiliza- tion (where the plants are closely related) is to transfer pollen from one flower to the pistil of another. It will be well to remove the stamens from the flower to be fertilized, with a pair of small forceps, before they have ripened, thus pre- [70] BURBANK IN THE ORCHARD venting self-fertilization. Then the pollen from another flower may be dusted on a watch crystal, and thence transferred with the finger tip or with a small eamel's-hair brush to the pistil of the flower to be fertilized. Cover the pistil thoroughly with pollen, and there will be little danger that any foreign pollen may subsequently find lodgment; particularly if the petals of the flower are cut away, so that it will no longer attract bees. Mr. Burbank sometimes saves time, in the case of orchard fruits, by operating on a blossom just before it opens, cutting it across with a sharp knife in such a way as to remove the pollen- bearing anthers at the ends of the stamens, care being taken not to injure the pistil at the center of the flower. Pollenation is then effected (after the pistil ripens) in the way just described. In operating on a large scale, Mr. Burbank does not find it expedient to cover the flowers with paper bags, nor does he think it necessary to do so. But the amateur who has plenty of time at his disposal may give the flowers this added pro- tection if he so desires. The object is simply to make sure that the bees do not accidentally trans- fer pollen to the pistil, and thus perhaps compli- cate the experiment. Such cross-pollenation, through which the strains of various races or species of orchard fruits are blended, constitutes a very essential part of Mr. Burbank 's work. In this way he has brought together the racial strains of plums from [71], LUTHER BURBANK Japan and Europe, and blended them with those of American plums, producing extraordinary new varieties; and the strains of apples, pears, peaches, quinces, and cherries, from the most widely separated geographical regions, have been similarly blended. CEEATING NEW FRUITS One time when Mr. Burbank was a young man he was browsing in a San Francisco library, and came across an account, written by a wandering sailor, of a remarkable red plum found in Japan, and spoken of by the sailor as the " Blood Plum of Satsuma." Mr. Burbank at once sent to Japan for this plum, among others, and he ultimately secured a specimen, which became the progenitor of all the different varieties of red-fleshed plums that are now to be found anywhere in America. Some of the other Japanese plums, — and the Chinese plum as well, — when blended with Amer- ican and European plums, were equally notable as producers of new and remarkable varieties. Of the sixty odd new varieties of plums and prunes that Mr. Burbank has introduced, no fewer than thirty-eight bear strains of the Asiatic plums, fourteen were developed from American stock, and thirteen from European species. But the various strains have been intimately blended. A single complex hybrid may reveal the brilliant color and delicious fragrance of the Chinese plum, the red fruit pulp and large size of the Japanese, [72] BURBANK IN THE ORCHARD the hardiness and fine flavor of an American wild plum, and the sweeetness of a European pro- genitor. By hundreds of carloads, in the aggregate, the various Burbank hybrid plums are sent to the eastern markets each season. One of Mr. Burbank 's most celebrated experi- ments was that in which he hybridized the plum and the apricot, producing a wonderful new fruit, the plumcot. The hybridization was effected with difficulty, because the two strains were so dis- tantly related, but it was finally accomplished, and now there are many varieties of plumcots in the orchards at Sebastopol. Among the new varieties that Mr. Burbank has developed by this method, none perhaps has ex- cited more general interest than the stoneless plum. A fruit that exteriorly looks like any other plum, yet which offers no resistance to the teeth when you bite right through it, is obviously some- thing quite out of the ordinary. The stoneless plum was developed by a long series of hybridizing experiments in which the original progenitor was a small "freak" plum of acrid and inedible quality, that through some abnormality was partially stoneless. This little plum grew wild in France, and was not consid- ered of any value. Mr. Burbank secured a speci- men, however, and hybridized its blossoms with various cultivated plums. The problem was, to breed into the hybrid the qualities of the commercial plum, while retaining [73] LUTHER BURBANK and accentuating the tendency to stonelessness. This proved exceedingly difficult. But by per- severing through a long series of generations, sav- ing always for seed purposes the seedlings that showed most improvement, and grafting them in the way above described to hasten their develop- ment, Mr. Burbank finally succeeded in producing not merely one variety, but several varieties of plums and prunes of large size and of excellent quality that are almost absolutely stoneless, re- taining at most a tiny fragment of shell at one end of the seed. Some varieties have shown a marked tendency to eliminate the seed itself as well. The contrast between the cranberry-sized par- tially stoneless French plum, with its inedible flesh, and the mammoth stoneless plum of delicious quality that is descended from it is very striking. SUGGESTIONS FOB THE AMATEUR The development of such a fruit required years of time and an almost inexhaustible supply of energy and patience. But the principles involved, from first to last, were merely those that have been outlined above. Hybridization and selection — these are the methods of the fruit developer as perfected by Mr. Burbank. Intelligently inter- preted and systematically followed up, they make possible almost any desired transformation in plant life. jLet this not be misunderstood, Selection of [74] BURBANK IN THE ORCHARD material and the right blending of the material are the essential methods of the plant developer. But the creative work of a master painter might be described in the same terms. In each case, everything depends upon how the materials are used. The " wizardry " that one hears ascribed — and very justly ascribed — to Mr. Burbank has for ac- cessories the methods of hybridization and selec- tion, but these are applied with (1) the creative genius that can conceive the ideal of a specific plant development, plus (2) prevision in selecting forms to hybridize, plus (3) a sixth-sense intui- tion in noting nice shades of variation, plus (4) indefatigable energy .in following up an experi- ment, and inexhaustible patience in the face of temporary bafflement. In a word, certain mechanical methods plus genius account for the work of Luther Burbank. But the mechanical methods, after all, are essen- tials. You cannot become a master painter merely by inspecting the palette of a great artist; but you can never hope to paint at all if you do not learn the rudiments of pigment-mixing. Sim- ilarly you will not necessarily become a Burbank because you learn to hybridize and select, but you must learn these things if you are to attempt plant development at all. Moreover, here, as in many other fields, you may repeat an experiment that you might not have preconceived. Many an amateur can make a fairly presentable copy of a masterpiece. [75] LUTHER BURBANK Each of Mr. Burbank's great plant develop- ments is a masterpiece of experimental applica- tion. Yet many of these developments might be duplicated, now that the methods are known, by any intelligent amateur who will give attention to details. It is possible for you to apply the methods on a small scale even though you have but a single fruit tree. Indeed, with a ten-foot plot of ground for the raising of seedlings, and a single tree on which to graft, you may experiment to your heart's content. And although you cannot expect to produce plumcots or stoneless plums or superlative varie- ties of peaches or apples or pears or cherries without expenditure of effort, you may at least hope to develop interesting modifications in the fruits with which you operate, even though you devote only an occasional half -hour to the experi- ment. You may secure any amount of material for the development of new varieties merely by plant- ing the first seeds of apple or pear or plum that come to hand. For the cultivated varieties of orchard fruits do not breed true from seeds. You will not secure Baldwin apples, for example, with any certainty, by planting the seeds of the Bald- win. But this is an advantage from the stand- point of the plant experimenter. You may make sure of interesting developments by planting the seeds of any orchard fruit that you secure in the [76] BURBANK IN THE ORCHARD market, and working with the seedlings along the lines suggested above. Mr. Burbank has used the wild crab apple in some of his experiments, and has produced a hybrid of large size, retaining certain qualities of the wild fruit. He has also developed an extraor- dinary plum, of enormous size and of almost in- credible productivity, by hybridizing the little beach plum with various cultivated varieties. These are experiments that you may duplicate with very little trouble, the results of which are sure to be surprising and fascinating. Even before the blossoms come, you may begin operations by grafting scions of good varieties on the branches of your old trees. Also, you should start at once germinating some seeds, to raise seedlings that will be grafted or budded on your trees later in the season. If, in addition, you will prune your old orchard trees thoroughly, and cultivate and fertilize the soil about their roots, you will have prepared the way for a crop of improved fruit the coming fall, and for a series of fascinating experiments in the development of new varieties. You may plant the seeds at once on taking them from the fruit, as soon as the fruit is ripe in the fall, provided you have a warm place in which to keep them over winter. Plant them in a box or can, in soil prepared according to Mr. Bur- bank's formula already given. They will thus get a good start, and will be ready for transplant- ing or for grafting in the early spring. [77] LUTHER BURBANK If, on the other hand, you keep the seeds over winter, they should be kept slightly moist, as they will not germinate readily, if at all, if they are allowed to become thoroughly dry. They may be kept in sand that is slightly moistened (not wet) in a cool place. The seedlings grown from seeds planted in the early spring will be ready to supply material for summer budding, or they may be left on their own roots throughout the season, to be grafted early in the succeeding spring. Meantime you may extend the scope of your operations, and prepare for a wider range of ex- periment next season, by hybridizing the flowers of any orchard trees that chance to grow in your dooryard. You may secure a few apple blossoms from your neighbor's orchard, and by pollenating the blossoms on your own tree prepare the way for interesting developments. Also, if trees are at hand, try pollenizing apple and pear, or pear and quince, or wild crab and cultivated apple, or wild plum and domestic plum, or wild cherry and cultivated cherry. There will be no obvious immediate effect on the flower that you thus cross-fertilize. The fruit that develops will be the same in appearance that it would have been if fertilization had been effected in the ordinary way with pollen of its own kind. But the seeds are profoundly affected in their germinal matter. You must extract the seeds when the fruit is ripe, and either plant them at once or keep them over winter as above suggested. The seedlings that grow from them will be hybrids [78] BURBANK IN THE ORCHARD combining the qualities of the two parent forms. Just what the result will be cannot be known until the seedlings are old enough to bear fruit, — which, if they are properly grafted, will be in their second or third year. Then surprises will be in store for you. Not even Mr. Burbank himself could predict what the new fruit may be like in a given case. But it is certain to be something different from either parent — a new form of plant life that you have brought into being by combining different racial strains. [79] CHAPTER V NEW BERRIES AND GARDEN FRUITS FEW aspects of Mr. Burbank's work have been more spectacular than those having to do with the production of new berries. He has hybridized the blackberry and the rasp- berry, producing new types of berry that are en- titled to rank as new species. He has also hy- bridized the strawberry and the raspberry, and has crossed the dewberry with such divergent forms as the apple, the pear, the mountain ash, and the rose. The last-named crosses produced remarkable plants, but these did not bear fertile fruit. It is quite within the possibilities, however, that some other worker may repeat these experiments, and produce berries as new and wonderful as the Primus berry, the Phenomenal berry, the Para- dox berry, or the white blackberry, these being four of Mr. Burbank's most wonderful creations. The way in which these berries were developed is here told in detail ; also the story of the thorn- less blackberry, the sunberry, and the improved cactus pear. The practical directions given will enable the amateur to improve any varieties of berries in his garden by selective breeding, and to produce new varieties that are different from [80] A CLEFT GRAFT. This reproduction of a color-photograph illustrates one of several common methods of grafting, as practiced in Mr. Burbank's orchard. The engrafted twigs are called "Scions," the branch on which they are placed is called the "Stock." The essential principle is that the inner bark, called the Cambium layer, of the scion, should be brought into intimate contact with the corresponding layer of bark of the stock. The work is completed by covering stock and scion with grafting wax, and wrapping cloth about the stock for further pro- tection. BERRIES AND GARDEN FRUITS any ever seen before, and superior to anything now in your garden, whether or not they rival the extraordinary ones that Mr. Burbank has created. CULTURE OF GAEDEN FRUITS The small fruits make a special appeal to the amateur, because they are so easily grown and do not demand so much patience in awaiting re- sults as do the orchard fruits. Any odd corner of your garden will afford op- portunity for a berry patch. Almost any soil will do, but that which is loose and loamy or sandy is best. It is Mr. Burbank 's custom to plant the seeds of raspberries and blackberries as soon as the fruit ripens. He merely crushes the fruit gently, washes away the pulp, and plants the seeds in boxes which are transferred to the greenhouse in the winter. They will thus make an early start in the spring, and you will gain several months' time. If you have not a greenhouse available, it will be necessary to wait till the following spring before planting ; but the seeds are not injured by drying. If the seeds are planted in boxes, transplant them when two or three inches high into rows about three and one-half feet apart, the individual plants being placed about a foot apart. Let the seedlings run wild until they come to fruiting age. Then rigidly destroy the plants that produce inferior fruit. [81] LUTHER BURBANK The plants selected for preservation may be trained on posts or trellises, and made to take any desired shape by nipping off the tips of stalk or branches. The old wood should be cut away from time to time. The best plants may be propagated by tips or by suckers. REMAKKABLE HYBKIDS The blackberry and raspberry represent two obviously related and familiar types of fruit, each of which has characteristic qualities. But there are many species of each group, and these may be interbred indiscriminately, offering the most inviting opportunities for the creation of new varieties. When Mr. Burbank fertilized the dewberry with pollen from the apple, the pear, the mountain ash, and the rose, he was carrying hybridization to something like its limits. The plants belong to the same family, but the dewberry is not of the same genus with any of the others. The fruit that formed was not visibly different from other dewberries. But strange potentiali- ties were blended in the seeds. The plants that grew from those seeds next season showed the most extraordinary range and variation of vine and leaf and flower. A few of them formed berries, but in all cases these berries were without seeds, or the seeds lacked the germi- nating kernel. In other words, the strange hy- brids were infertile. It would appear that the [82] BERRIES AND GARDEN FRUITS hereditary strains thus brought together were too widely divergent for compromise. A somewhat similar result was obtained when Mr. Burbank brought pollen from a strawberry flower and placed it on the pistil of the flower of a raspberry. The seeds of the raspberry were carefully preserved, and next season they germi- nated and produced plants which at first had all the appearance of the strawberry plant, but which subsequently sent up stalks not unlike those of the raspberry. The leaves of the curious hybrid, however, were always trifoliate, like the leaves of the strawberry. The plants blossomed, but formed only abortive berries that had no seeds. On the other hand, when Mr. Burbank fertilized the flower of the dewberry with pollen of a rasp- berry plant he had imported from Siberia, one of the numerous hybrid offspring showed great vigor, having a much larger leaf than either of its parents, and producing a fruit that also was much larger than that of either parent. This fruit was named the Primus berry. It has the outward appearance of a blackberry, but if al- lowed to remain on the vines until entirely ripe, it parts from the receptacle on being picked, just as a raspberry does. The Primus berry is a hybrid of the first gen- eration, which appears to blend the qualities of its parents in about equal proportions. Curiously enough it did not revert to the form of either parent in the next generation, though thousands [83] LUTHER BURBANK of seedlings have since been grown from it. On the contrary, it breeds true from the seeds — as true as any wild species, and far more true than most cultivated ones. Thus it gives every evi- dence of constituting a fixed species, sprung into being in a single generation. This is believed to be the very first new species of plant ever produced under conscious human direction. Its production marked an epoch in the history of plant development, — not because of the qualities of the Primus berry itself, which is of a flavor not generally appreciated, but because of the demonstration that a new species could be produced by hybridization. Instead of being infertile as hybrids were supposed to be, the new berry proved enormously productive. Another variation in application of the laws of heredity was illustrated when Mr. Burbank crossed the California dewberry and the Cuthbert raspberry. Here the hybrid progeny were of various forms, but they were all red in color, though the seed parent was the blackberry. The hybrids proved fertile, and a few of the best of them were preserved and inbred through suc- cessive generations. In the second generation one of these produced a berry of extraordinary size — perhaps the largest berry ever seen — which resembles a blackberry in general appearance but is bright clear red in color, showing the influence of the raspberry grandparent. This berry was named the Phenomenal. It has a fine flavor and has gained great popularity. [84] BERRIES AND GARDEN FRUITS This fruit is so different from either raspberry or blackberry that the nurserymen classify it with neither, but in a new group. The combination is so fixed that there is never reversion to either raspberry or blackberry in any generation. In other words, the Phenomenal berry also is a new species that breeds true. The Paradox berry has for its ancestors the Lawton blackberry and the Crystal White black- berry. The hybrid offspring of this union were selected and inbred through several generations, and the berry named the Paradox appeared in the fourth generation. Of these three remarkable new species of brier fruits, then, one is a first-generation hybrid, an- other a second-generation hybrid, and the third a fourth-generation hybrid. QUANTITY PEODUCTION It must be understood that in each case Mr. Burbank was dealing with large numbers of hy- brids, and that the berry finally selected and named was the best individual in a fraternity that included thousands or tens of thousands of indi- viduals. While the blackberry-raspberry experi- ments were under way, indeed, Mr. Burbank had occasion each successive season to select a few individuals as representing most nearly the ideal at which he aimed, the remaining plants being uprooted, piled in a heap, and burned. On one occasion no fewer than 65,000 hybrid [85] LUTHER BURBANK plants of the blackberry and raspberry were thus consumed. Many of these vines bore excellent fruit, but it was impractical to sell them or give them away, because some of the recipients would have been sure sooner or later to announce their fruits as " Luther Burbank's finest creation," to the dis- advantage of the purchaser and to the detriment of Mr. Burbank's reputation. The plant devel- oper himself never puts a new variety on the market unless he believes it to be superior to any existing variety in at last one respect, and equal to any other in all respects. His reputation has been made by following this rule, and he cannot afford to jeopardize it by allowing any new va- riety that does not conform to this test to be put on the market. Hence the necessity for the not infrequent " ten-thousand-dollar bonfires" through which the discarded plants that have entered into his experi- ments are destroyed. ' '"—»•*£? * When we learn that the original Paradox berry vine was the only individual saved among forty thousand hybrids, our first thought is likely to be that it is an almost hopeless task for the ama- teur to attempt to develop a new variety of small fruit. But it should be explained that the standard of the amateur need not be so high as the standard that Mr. Burbank establishes. Among the forty thousand discarded vines there were doubtless large numbers producing new varieties of berries [86] BERRIES AND GARDEN FRUITS that would have been highly satisfactory to almost any other experimenter. Mr. Burbank was looking for the one best berry, and he took no interest in a second-best. The amateur who is experimenting for his own pleasure rather than for the production of com- mercial fruits may well be satisfied if he produces varieties differing from any others hitherto in ex- istence, even though these new varieties should not chance to be of superlative quality under gen- eral culture. Yet it might be your good fortune to produce a new fruit of distinction at the very outset. In any event, you may without question improve the quality of any fruit in your garden if you will follow the methods that Mr. Burbank has developed. You may grow better berries than you ever grew before, and different ones from those of your neighbor, with no great effort — once you know how. NEW VAEIETIES TO ORDER The production of new varieties of genuine im- portance lies well within your grasp if you are willing to take the slight trouble involved in hy- bridizing different species of small fruits — fol- lowed by rigorous and persistent selection. For that matter, it is not necessary to do pollenizing, as the pioneer work has already been done with most of our small fruits, and selection alone, sys- tematically followed up, will bring interesting re- sults. Mr. Burbank 's remarkable Himalaya berry [87] LUTHER BURBANK was produced by selection, from seeds imported from India. Should you wish to stimulate further variation, however, you may practice cross-pollenizing. The method has been explained in connection with orchard fruits, and need not be repeated here. The only essential, it will be recalled, is the trans- fer of pollen from one flower to the pistil of an- other at a time when the pistil is mature, or ap- proaching maturity. The fruit in itself that grows from the flower thus cross-fertilized will not reveal the character of the pollen parent. If, for example, pollen has been brought from a blackberry flower to fertilize a raspberry, the raspberry fruit will be' the same in appearance as it would have been if the flower had been fertilized with pollen from another rasp- berry. But the seeds in the fruit will be profoundly changed in nature, though in no way altered in exterior appearance, and the vines that grow from them next season may show at once the evidence of their hybridity. Just what will be the char- acter of the fruit they will bear can never be predicted, and this uncertainty gives added in- terest to the experiment. As a rule, it is well in hybridizing two plants to make what is called a reciprocal cross — that is to say, use pollen from each plant to fertilize flowers of the other plant. But it is the general experi- ence that the hybrid offspring have the same char- acteristics whichever way the cross is made. [88] CULTIVATING THE FRUIT ORCHARDS The view is taken at Sebastopol. It shows modern fruit trees trained to such manner of growth that they permit the plow to run close to their trunks. This is an experimental orchard, and the trees are planted closer than they would be in a commercial orchard, giving opportunity for abundant selection BERRIES AND GARDEN FRUITS Mr. Burbank's experiments show that it is pos- sible to effect hybridization between all the dif- ferent varieties of blackberries and raspberries, and that interesting new varieties are produced in almost endless profusion. There is perhaps no other field that offers a readier opportunity for interesting experiments. Anyone who has a few bearing plants of the blackberry or raspberry in his garden has an equipment adequate for all his needs. If you have plants of a single variety only, you may readily secure pollen of another variety from the plants of a neighbor, and thus an experiment may be inaugurated that is almost certain later to produce fascinating developments. It is even within the possibilities that you may produce a berry as unique and remarkable as Mr. Burbank's Primus or his Phenomenal or his Himalaya. Short of that, you are certain to de- velop hybrid forms that differ in some respect from either parent. And the novelty of having a berry that is different from anything ever seen before will be adequate reward for the compara- tively small effort involved. It is stimulative to recall that the Loganberry, representing a new type of fruit that has found its way into thousands of gardens, was a chance hybrid between a raspberry and a blackberry cross-fertilized by the bees. If an insect can thus create a remarkable new species, what may not you hope to accomplish? [89] LUTHER BURBANK SOME PRACTICAL HINTS In developing a hybrid you must of course grow the plant from the seed — preferably planted fresh from the berry as already suggested. But when you have secured a plant that bears fruit of ex- ceptional character, you may propagate it in- definitely by root division, or, as already stated, by tips or suckers. Thus you may stock your garden with any new variety you develop, regardless of whether it will breed true from the seed. But of course if you wish to accomplish further improvement you must make further selection and grow other seedlings ; and from this second selection after crossing your best results are likely to be obtained. Variations appear only among seedlings, — ex- cept in rare cases of "bud sports," — and variation is the basis of all plant improvement. You will do well, then, to study the character- istics of the different plants in your garden, and select for further experiment those that show some variation that appeals to you, — prolific bear- ing, or early bearing, or large size of fruit, or de- liciousness of flavor. Whatever the quality, you may confidently ex- pect that it will be reproduced and accentuated in some individuals of the progeny of the plant grown from the seed. By selecting the best of the offspring, in the same way, to furnish seed for yet another generation, you may presently develop a variety that has the particular quality in ques- [90] BERRIES AND GARDEN FRUITS tion as one of its most pronounced attributes — although the specimen with which your experi- ment began may have shown only the faintest trace of it. You may thus develop a new flavor, for ex- ample. Or you may double or quadruple the size of the fruit. The secret of success is to select rigidly plants that show variation, and breed from them. One very important thing to understand, how- ever, is that your selection should be based not on an individual berry, but on the average product of a vine. A single fruit may chance to grow under exceptional circumstances — alone on a vine, or particularly favored by light or nourishment — and so may attain what might be called abnormal proportions. Such a fruit is not more likely to produce large progeny than the smallest, meanest fruit on the plant. It is heredity that counts, not the peculiarities of an individual plant. But if you find a plant whose average product is larger than the ordinary, you may with con- fidence save the berries of that plant for seed, and you will almost surely get some seedlings that will bear berries even larger than those of the parent plant. Even if there is not much improve- ment in the first generation, there is likely to be a cumulative effect with successive generations, and a time will come when striking results will be apparent. Mr. Burbank speaks of this cumulative tendency as "the momentum of variation." It has often [91] LUTHER BURBANK given him remarkable new varieties suddenly, after a series of breeding experiments that for a time gave little promise. The ultimate product may differ so widely from the first form as fully to justify reference to it as a "new creation. " There is one other important point to be borne in mind in developing a quality through selection in the way just suggested : namely, that you must inbreed the plants that are developing the new quality, once the variation is manifest. Suppose, for example, you have found a rasp- berry vine in your garden that bears fruit that is very large and of exceptional sweetness. You wish to accentuate these qualities. Now, instead of cross-fertilizing, you do just the opposite. You take pollen from a flower of your choice vine and carry it to the pistil of another flower on the same vine. Or you bring pollen from a closely related plant of similar qualities. This is called inbreed- ing, or "line breeding." You must combine forces, as it were, and ac- centuate the quality that both parents present in exceptional degree. By cross-breeding (say at an earlier stage of the same experiment) you pro- moted variation, and laid the foundation for new varieties. By inbreeding you limit variation, ac- centuate a given quality, and fix a type, — turn- ing the forces of the plant in the desired direc- tion. One method supplements the other, and Mr. Burbank's most successful experiments in plant development always include both methods. [92] BERRIES AND GARDEN FRUITS MAKING A WHITE BLACKBEEEY Let us see the methods applied by Mr. Burbank in one or two typical experiments. Take, for in- stance, the case of the white blackberry. This is one of Mr. Burbank 's most interesting (though not most useful) small-fruit developments. We may briefly trace its pedigree. It appears that a small brownish-white black- berry was found growing wild in the eastern states, and introduced by a New Jersey firm a good many years ago as a curiosity, under the name of the Crystal White blackberry. Notwith- standing the name given it, the fruit was by no means white, and it was of very inferior quality as to size and flavor. It occurred to Mr. Burbank, however, that he might be able to improve the quality of the fruit and remove its traces of brownish pigment. In attempting to accomplish this, Mr. Burbank hybridized the little berry with the Lawton black- berry. The hybrid offspring all bore berries that were black in color. In the second generation, however, there appeared a small proportion of vines that bore fruit that was almost white, and yet was of fair quality. These vines, being inbred, gave in the next gen- eration berries that were pure white and of large size and excellent flavor. What had happened, in effect, was that the good- fruiting qualities of one ancestor had been com- bined with the unpigmented fruit of another [93] LUTHER BURBANK strain; and this was precisely the combination that the plant developer was seeking. Meantime the cross-breeds varied widely, and some of them showed a tendency to vigorous growth and pro- lific bearing. Of course, there were numberless others that showed undesirable combinations, but these were destroyed, and only the plants having the desired qualities in the best possible combina- tion were preserved. By inbreeding these for a few generations, the new qualities were accentu- ated and fixed, and a race of white blackberries which always come true from the seed was estab- lished. Let it be particularly noted here that the new berry, as finally developed by selection, combines the traits of two widely different ancestral strains and accentuates them, while eliminating other an- cestral traits. It has the juiciness and sweetness of flavor of the Lawton blackberry ; and it is snow- white, whereas one of its ancestors was black and the other a brownish-white. By selective breed- ing, all trace of pigment has been eliminated from the species. It will be obvious that this selecting out of cer- tain qualities from different ancestral strains and reasserting them in a hybrid progeny, with the elimination of other ancestral traits, is a very in- teresting and very remarkable phenomenon. Mr. Burbank early discovered that it is possible thus to segregate the qualities of different parents and recombine them, accentuated, in the hybrids of a second and a few subsequent generations. The [94] BERRIES AND GARDEN FRUITS application of this principle enabled him to pro- duce a large number of his most important new varieties of all kinds of plants. He decides in advance what qualities he wishes to perpetuate and what ones he wishes to eliminate, and by selecting among large numbers of seedlings he is enabled to secure the ideal plant that he has in mind. But it must not be supposed that Mr. Burbank's success is due merely to the recombining of desired fruit characters already present in one parent or the other. On the contrary, such segregation and recombination of traits constitutes only the begin- ning of his task. This does, indeed, supply him with varying material with which to work ; but as a rule he would not produce a fruit of commercial value did he not extend the experiment by se- lective breeding among the individuals that have the desired quality in the most pronounced degree. Line breeding them intensifies these qualities ; so that, for example, the Burbank white blackberry is snow-white, whereas its so-called " white " an- cestor was dull brownish-white, and at the same time it has the excellent qualities of the Lawton. THE THOBNLESS BLACKBEEBY It was through application of the same princi- ples that Mr. Burbank was enabled to develop his wonderful thornless blackberry, perhaps the most important of his plant developments in this par- ticular field. Anyone who has had experience of [95] LUTHER BURBANK a brier patch will readily conceive that the pro- duction of a thornless brier is a work of genuine importance. Mr. Burbank's thornless blackberries, as al- ready stated, have absolutely smooth stems. There is not the remnant of a thorn anywhere about them. They are as smooth as pussy-willows. They are the forerunners of a race of thornless brambles that will doubtless supplant the old thorny kind everywhere in the near future. The parent form with which Mr. Burbank worked in producing these anomalous plants was a nearly thornless but otherwise worthless dew- berry that was discovered growing wild in North Carolina. The botanist who discovered the plant gathered some of its fruit and sent it to Mr. Bur- bank, thinking he might care to experiment with it. The fruit in question was of poor quality and, as in the case of the white blackberry, it was neces- sary to breed altogether new qualities into it. The problem, of course, was how to retain and accentuate the tendency to thornlessness of plant that was the sole recommendation of this par- ticular variety of dewberry, and at the same time to place berries of good commercial qualities on these plants. When the thornless dewberry was hybridized with other blackberries, the hybrid offspring were all thorny, just as the offspring of the black and the white blackberries were all black. But thornless progeny reappeared in the second gen- eration, and some of these bore fruit of a better [96] THE PROCESS OP GRAFTING COMPLETED After the scions are inserted, grafting wax is applied, and the end of the stock is bound up with cloth, to give it added protection while its wounds are healing. LUTHER BURBANK veloped by Mr. Burbank from seed imported from India, and hence named the Himalaya berry. A single plant may produce several hundred pints of berries in a season. But the vine is armed with very stout recurved thorns, making the gathering of the berries a somewhat difficult and decidedly disagreeable task. It should be possible by hybridizing this plant with the thornless blackberry to produce in a later generation a plant combining the vigorous growth and prolific bearing of the Himalaya with thorn- lessness. Mr. Burbank has made this cross, and he has also crossed the thornless blackberry with the white blackberry. He has many thousands of seedlings of both type now under test that will give new varieties of thornless berries when fully educated. He has also seedlings from a new cross of the Japanese Balloon-berry and a rasp- berry from Hawaii, and scores of other berry seedlings of new combinations. It is not unlikely that in the course of these experiments there will develop berries with quite unpredicted qualities. For Mr. Burbank has shown over and over that where plants from widely separated geographical regions are brought together the offspring are likely to mani- fest extraordinary vigor, and to reveal traits of the most unexpected character. The hybrid seedlings of the Balloon-berry and the Hawaiian raspberry grow so rapidly as soon to overshadow their parents. Such enhanced capacity for growth is shown by various of Mr. [98] BERRIES AND GARDEN FRUITS Burbank 's berry hybrids and often extends to the fruit itself, as in the case of the Primus berry and the Phenomenal berry, already noted. So there is every prospect that any hybridizing experiments you may undertake with blackberries or raspberries in your garden will produce new races, a certain proportion of the individuals of which will excel the parent forms very markedly in vigor of growth and in size of fruit. OTHEB SMALL FRUITS THAT AWAIT DEVELOPMENT Doubtless the blackberries and raspberries offer the most inviting opportunities for experiment, yet we must by no means overlook the other small fruits that are to be found in the amateur's gar- den. The strawberry, for example, may be hy- bridized quite as readily as the other berries. In particular it would be well worth while to repeat Mr. Burbank 's experiment of cross-pollenizing the strawberry and the raspberry. A similar cross might be attempted with the blackberry, now that Mr. Burbank has developed a strawberry that bears throughout the season. Hitherto it would have been difficult to find strawberries and black- berries blossoming at the same time. It is true that Mr. Burbank 's celebrated experi- ment in crossing the strawberry and the raspberry produced only infertile hybrids. But it is quite within the possibilities that greater success might attend another series of experiments. And it re- quires no argument to show that a fruit that com- [99] LUTHER BURBANK bines the qualities of the strawberry and the rasp- berry would be a very valuable and interesting acquisition. If you will take the trouble to fertilize the flowers of the raspberry and blackberry with pollen of the strawberry (it would be well to make the reciprocal crosses also) it may fall to your lot to produce a fertile hybrid that will be as unique and remarkable an addition to the list of small fruits as is, for example, Mr. Burbank's plumcot among orchard fruits. Again, we must not overlook the currants and gooseberries. These have small flowers, and hence are not quite so easy to work with. But with the aid of a magnifying-glass they may read- ily be cross-pollenized, and there is ample oppor- tunity for the development of new varieties. It is particularly desirable, for example, that goose- berries should be developed that are without the disagreeable hairs or prickles that most varieties of this fruit bear, also without thorns on the bushes. A sweet and high-flavored gooseberry would also be welcomed. Plants that are resistant to mildew are also to be desired. Mr. Burbank has shown that the different cur- rants and gooseberries may be cross-fertilized readily. There are numerous varieties under cul- tivation that may be used in hybridizing experi- ments, and there are also wild species to be found in many regions that might advantageously be tested. In many cases a wild species has qualities of hardiness and vigorous growth that may ad- [100] BERRIES AND GARDEN vantageously be blended with the size and flavor of fruit of the cultivated varieties. So it might be possible, by hybridizing the cur- rants and gooseberries with wild species, to pro- duce new types of berries that would retain the attractive qualities of the currant, yet would be as large, let us say, as cherries. Here again the field is one that any amateur may readily enter, now that Mr. Burbank has shown the way. A few years ago it would have been thought ridiculous to suggest that our common fruits might thus be modified and developed into new forms with comparative little effort, and in the course of two or three generations. But Mr. Bur- bank has shown that such modifications may be brought about, making the demonstration thou- sands of times over, until no opportunity for skepticism remains. And, as already suggested, there is perhaps no other field that offers more inviting opportunities than those that are to be found in the ordinary small-fruit garden. SOME NEW FEUITS As illustrating the possibility of making addi- tions to the list of garden fruits, mention may be made of Mr. Burbank 's sunberry, which is a hy- brid between two forms of nightshade, neither of which produces edible fruit. This new berry, which is particularly prized for the making of pies, — it closely resembles the blue- berry in flavor, — is a brand-new addition to the [101] LUTIIER BURBANK list of edible fruits. It was produced as a fixed new species in the first generation, through hy- bridizing two forms of nightshade; one of them from Africa, the other a weed-like plant indige- nous to America or long ago introduced from Europe. The hybrid is in a good many ways in- termediate between the parent forms, but it dif- fers from either of them in that its berries are edible. Some confusion has arisen through the change of name, unauthorized by Mr. Burbank, which led to the placing of this fruit on the market as the "Wonderberry," and through the confusion of the new fruit with other species of nightshade to which it is only distantly related. The night- shade family, it should be explained, has poison- ous members, and so is of ill repute. But it should not be forgotten that among the wholesome repre- sentatives of the family are the familiar garden vegetables, the potato, the tomato, and the egg- plant. From the standpoint of the plant developer, perhaps the chiefest interest associated with the sunberry hinges on the fact that the hybridization through which it was created was accomplished only after many years of unsuccessful effort. In- deed, Mr. Burbank had attempted to cross-fertilize the parent forms, quite without success, for some- thing like twenty-five years, before he at last suc- ceeded in fertilizing a single flower and producing a single berry from which the new race was de- veloped. [102] BERRIES AND GARDEN FRUITS Mr. Burbank is constantly experimenting with other wild plants that have more or less inedible fruits. He has in recent years conducted a very elaborate series of investigations with different varieties of elder, and is developing varieties that produce berries very much improved in size and quality. He is confident of producing a valuable commercial fruit, and the fact that the elder is a hardy ornamental shrub gives added value to the experiment. Another line of experiment that promises good results is being made with the different species of passion flower. This subtropical vine has been chiefly prized for its flower, but it bears a fruit that is edible, and the quality of this fruit is being improved by cross-breeding experiments in which species from different parts of the world are utilized. THE MOST PROLIFIC FRUIT-BEARER But by far the greatest of Mr. Burbank *s recent triumphs in the production of new fruits is that associated with the development of the fruit of the cactus, and in particular those new hybrid cac- tuses of the genus Opuntia that have been relieved of their spines. The development of the spineless cactus through a long series of experiments in hybridizing and selection constitutes one of the most remarkable of Mr. Burbank 's achievements in recent years. The slabs of the perfected varieties are as smooth [103] LUTHER BURBANK as the palm of the hand, and they constitute a remarkable addition to the world's forage crop, particularly adapted to arid regions. While developing these spineless races, Mr. Burbank paid attention to the fruit as well, and he has developed many varieties of cactus fruit varying in appearance and quality almost as widely as do the different varieties of cultivated apples or pears. Some of the cactus fruits are white in color, others yellow, yet others a brilliant crimson. The flesh is juicy and palatable. As yet the prickles have not been entirely removed from the skin of the fruit, but Mr. Burbank has plants now under development that he is confident will bear perfectly smooth fruit. It required a little longer to take the spines off the fruit, because the cactus does not bear fruit until it is four or five years old, and it was necessary to let each suc- ceeding generation come to maturity before the quality of its fruit could be determined. Meantime the prickly or smooth condition of the slabs of the plant could be observed from the outset, and selection for this quality could be made while the seedlings were very small. But in the end the spines will be removed from the fruit as effectively as they have been removed from the foliage of the plant ; such, at any rate, is Mr. Burbank 's confident expectation. In the size of its product, the cactus is to be compared with the orchard fruits rather than with the berries. But the cactus, in its perfected varieties, is admirably adapted for growth in the [104] A BRAND NEW BURBANK FRUIT— THE PLUMCOT. This beautiful reproduction of a direct-color photograph shows one of the choice varieties of Mr. Burbank's new fruit, the Plumcot, produced by hybridizing the plum and the apricot, and representing the only new type of orchard fruit that has been developed within historic times. BERRIES AND GARDEN FRUITS garden, and it has many attractive qualities. It is enormously productive, thrives under the most adverse conditions, and bears a fruit so different from any other of the products of the garden as to have double attractiveness. A single plant will bear all the fruit that a good-sized family could use. Sometimes half a hundred fruits are borne on a single slab. The best of Mr. Burbank's fruiting varieties bears, on good soil, at the rate of more than one hundred tons per acre. Unfortunately the new fruiting cactus plants are not very hardy, but whoever lives in a region to which they are adapted will find this a valua- ble addition to the fruit garden. Meantime there is opportunity for further experiment in selective breeding with an eye to the production of hardier varieties. There are varieties of cactus that thrive in the coldest regions, and it is probable that by using these in hybridizing experiments new varieties might be developed that combine the fruiting qualities of Mr. Burbank's new cactuses with the hardiness of the other parent. Mr. Burbank him- self has experiments under way looking to this end, but there is no reason why his efforts should not be supplemented by those of many other workers. The cactus is a comparatively easy plant to hybridize, its flowers being large and conspicuous. It is necessary, however, to watch the flowers closely and cross-fertilize them at once when they [105] LUTHER BURBANK open, before the bees have time to forestall your efforts. Except for the development of new varieties, the cactus should not be grown from the seed, as, like other cultivated fruit-bearers, it does not breed true. But the slabs take root readily, — especially if dried somewhat before planting, — and the plant may thus be propagated indefinitely, all the offshoots reproducing the qualities of the parent form. [106] CHAPTER VI BUEBANK IN THE VEGETABLE GAEDEN IN this chapter are detailed the methods of selective breeding through which improved types of vegetables of many kinds may be produced in your garden. Among the most remarkable of Mr. Burbank's experiments were those in which he grafted to- mato plants on roots of potatoes and potato vines on roots of tomato vines. The resulting fruits and tubers were extraordinary and unlike any- thing seen before. These experiments may be re- peated by anyone who will follow out the com- paratively simple methods of grafting described. The feat of hybridizing the blossoms of potato and tomato has not yet been accomplished, but this is among the possibilities, and the results are sure to be extraordinary. The members of the squash and melon family offer interesting possibilities of hybridizing, and these experiments may easily be carried out by anyone. New types of peas and beans may readily be produced; and experiments of a fascinating character may be performed with various varie- ties of sweet corn. In fact, there is scarcely a plant in the vegetable garden that does not offer opportunities for interesting experiments. [107] LUTHER BURBANK THE BUKBANK POTATO Doubtless you have eaten the Burbank potato, although you may not know it by that name. Mr. Burbank developed this new variety when he was a very young man, and it has come to be grown so universally that most people who cultivate it know nothing of its origin. The Department of Agri- culture estimated that up to 1906 not less than seventeen million dollars' worth of Burbank po- tatoes had been grown in the United States. This was Mr. Burbank ?s first important plant develop- ment, and for that reason also it has exceptional interest. Unlike many of his later developments, the new potato was produced without the necessity for a long series of preliminary experiments. It was, in a sense, a discovery rather than a creation, and as such it has added interest for the amateur, inasmuch as it suggests the possibility of finding in any garden extraordinary things if only we search for them. The extraordinary thing that Mr. Burbank found in his Massachusetts garden when he was scarcely more than a boy (it happened in 1873) was a seed ball growing on one of his potato vines. Everyone knows that the potato is propagated by planting pieces of the tuber itself, and that ordinarily the potato vine does not produce seed. In very rare instances, however, a seed cluster does form, but it requires the imaginative mind [108] IN THE VEGETABLE GARDEN of a Burbank to conceive that there is any im- portance in this exceptional phenomenon. Most gardeners would have paid no attention to the seed ball, but Mr. Burbank watched it attentively, and determined to find out what would happen if the seeds were planted. His plan was nearly frustrated by the loss of the seed ball, which was broken off by some boy or animal or by the wind just as it ripened. After patient search the treas- ure was recovered, however, and carefully pre- served over winter. There were twenty-three seeds in the cluster, and these were planted next spring, each one by itself, and the vines that grew from the seed were carefully cultivated. In the fall, when the potatoes were dug, it was obvious that they represented twenty-three differ- ent varieties. No two hills were alike in size or appearance or abundance of their crop. And two of the hills bore potatoes of altogether exceptional size and quality. These were preserved and planted another season, and it was demonstrated that the tubers would reproduce their qualities, constituting a new variety, larger in size, whiter, smoother, and more uniform in shape than any existing variety. To illustrate the element of chance that enters into the work of the plant developer, it may be added that whereas the remarkable Burbank po- tato was thus developed in a single season merely by planting seeds that developed quite inde- pendently of human effort, forty years of subse- [109] LUTHER BURBANK quent effort, in which vast numbers of hybridizing experiments have been performed, have failed to produce another variety of potato superior to the one that was virtually a gift of nature. In this field of endeavor, as in so many others, there is an element of uncertainty that adds to its charm. Very recently, however, Mr. Burbank has ex- perimented with wild species of potato from South America, and has produced some remarkable new varieties that are about to be introduced. MAKING A PEA TO OKDER As illustrating about as striking a contrast to the story of the potato as could be found, we might cite the story of the Empson pea. Mr. Burbank was asked by a canner of peas to produce a new variety in which the individual peas would be small but uniform in size ; in which they would be uniform as to number in the pod; and would mature at the same time, so that the entire crop could be gathered at once, it being the method in the modern cannery to cut the vines by ma- chinery, carting them to the cannery like loads of hay. Of course it was essential that the peas should retain their quality of sweetness of flavor, and that the vines should bear an abundant crop of pods. Mr. Burbank was able to meet these specifica- tions in a period of only three years, by raising two crops of peas each season. And he did this purely by selection, raising large quantities of the [110] IN THE VEGETABLE GARDEN vines, and searching attentively among them for the individual vine that bore a crop coming nearest to the specifications. All the other vines were de- stroyed, and the new races of peas finally devel- oped were descendants of the one best vine. In each succeeding generation the inferior vines were similarly destroyed, and the best individual speci- mens preserved. The vines of the sixth generation were prac- tically uniform and met the specifications as to abundant crop of peas of designated size and quality, maturing at the same time. But while Mr. Burbank was developing this new race of peas, he developed also from the same set of vines four other races, some of them bear- ing large peas, others lentil-shaped ones, merely by selecting generation after generation with these qualities in mind. The point is simply that in any row of peas in your garden, grown from the same lot of seed, there is a wide range of variation, which the aver- age gardener quite ignores. But the attentive eye notes that some vines grow abundant crops and others scanty crops; that some of the pods are large and some small; and that as regards almost any given quality of the pea there is diversity, even though the peas are all classified as belonging to the same variety. If you will select and save separately the peas from half a dozen different vines, you may de- velop as many different races of peas in the course of a few generations. You may produce a variety [111] LUTHER BURBANK of predicted quality, as Mr. Burbank did in the case of the canning peas, or you may, as it were, follow where the peas lead you, and let the po- tentialities of the different varieties reveal them- selves as you proceed. SELECTION WITHOUT CEOSSING This important point must be borne in mind, however — and it applies not merely to peas but to all other plants. In making your selection, it is necessary to consider the total product of a given plant, not merely an individual fruit. A single pod of peas may be of exceptional size because it chanced that it is the only pod on a vine, or be- cause some other accidental circumstance favored it. The progeny of these peas will not necessarily tend to produce a race of large peas. But if you find a vine that produces pods that are uniformly of large size, this will indicate that the tendency to produce peas of this character is in the heredity or germ-plasm of this particular vine, and will tend to be transmitted. It should be observed that in producing these new varieties of peas Mr. Burbank worked purely by selection, without finding it necessary to hy- bridize the plants to produce new tendencies to variation. The plants tended to vary sufficiently to give him material for his experiments, and such is found to be the case with a very large number of plants in the yegetable garden. [112] MR. BURBANK'S PHENOMENAL BERRY This remarkable berry is virtually a new species produced by hybridizing the California dewberry and the Cuthbert blackberry. IN THE VEGETABLE GARDEN Quite generally you will find that there is a wide range of variation in the plants grown from the same lot of seed, and you may develop new varieties merely by selecting those individuals that exhibit the desired quality, saving their seed and selecting again for the same quality among the progeny. In the case of the pea, and its cousin the bean, the experiment is simplified by the fact that the plants are normally self -fertilized. If you will examine the flower of the pea or bean you will see that its stamen and pistil are encased in a closed floral envelope, to the interior of which bees and other insects cannot readily gain access. Nor- mally each pistil is fertilized by pollen from the stamens that grow beside it. In other words, there is the closest inbreeding, and there is no danger of introducing varying strains of other plants by cross-fertilization. The case is radically different, for example, from that of the squashes and melons, which are so readily cross-fertilized that it is exceedingly dif- ficult to keep the strains of any variety pure if other varieties are grown anywhere in the neigh- borhood. The bees are almost certain to carry the pollen of one kind of melon or squash to the pistil of another, bringing the pollen perhaps from flowers a quarter of a mile away; so you will ex- perience constant disappointment in growing crops of melons or squashes from the seed, unless you carefully shield the blossom from such con- tamination through cross-pollenizing. [113] LUTHER BURBANK If you wish to keep your strain of melons or squashes pure, you should carry pollen from one flower to another with the finger tip or with a camePs-hair brush, and then cover the flowers with a paper sack until they are past the time of receptivity. On the other hand, if you wish to experiment with varying races of melons or squashes, you have but to leave the work of cross-fertilization to the bees, and your seeds next season will give you as strange and variant a lot of material as you could desire. But there is no such difficulty with the peas and beans. These, as just stated, are protected against cross-fertilization by the character of their flower, and thus it is compara- tively easy to maintain a pure strain, once it is established. HYBEIDIZING PEAS AND BEANS If you wish, however, to extend your experi- ments with peas and beans, causing them to vary and thus to supply new material for selection, you may readily do so by the method of artificial pollenation. For although the floral envelope is closed against the bee, you may readily enough open it, and the pollenizing of the flower then pre- sents no difficulties. You may pluck away the stamens and deposit pollen from another flower on the pistil, precisely as you would do in the case of any other blossom. Tie a string loosely about the stem on which [114] IN THE VEGETABLE GARDEN this blossom grows, with a label naming the va- riety used as the pollen parent, and preserve the seeds for planting next season. Some of the most interesting and important plant experiments have been made with the gar- den pea in this way, notably the celebrated ex- periments of the Austrian monk, Mendel, which led to his discovery that some characters are " dominant " and others " recessive " in heredity, and that the recessive characters reappear in a certain number of the progeny of the second gen- eration. Mendel found, for example, that if a pea grown on a tall vine was hybridized with one grown on a short vine, the progeny of the first generation would all be tall, — tallness of vine being " dom- inant. " But the recessive trait of shortness, al- though submerged in the hybrid of the first gen- eration, will appear in one individual in four of the offspring of the second generation. It is obvi- ous that the fact that the flowers are self -fertilized simplifies the experiment, insuring that the hy- brids shall be inbred, and preventing the intro- duction of new hereditary strains that might com- plicate the results. Some of Mr. Burbank's earliest experiments were made with different varieties of beans. For example, he hybridized two varieties of bean, one of which produced a crimson pod with red beans and the other a crimson-and-white-striped pod with red-and-white-striped seed. Curiously enough, the hybrid beans were jet black in color, [115] LUTHER BURBANK unlike either parent. But in the succeeding gen- eration the offspring of the black bean broke up into new groups, some of them producing black beans, some red, some speckled, and some white. There were corresponding variations as to size and shape of the beans, and as to time of ripening. Meantime the hybrid vines showed the enhanced vitality that is somewhat characteristic of hybrids. They grew enormously, outstripping their parent by eight or ten feet. But the vines of the second generation were extraordinarily diversified, some of them growing with great vigor and others being dwarfed, and of such stocky growth that their pods trailed the ground. In another experiment Mr. Burbank hybrid- ized the pole bean and the lima bean, and the hybrid showed at first the characteristics of both parents, but subsequently took on the form of the pole bean. Mr. Burbank notes that this case is somewhat comparable to that in which he hy- bridized the strawberry and the raspberry. In that case the vines were at first like the straw- berry, and then shot up like raspberry plants. The case of the hybrid beans that showed both gigantic and dwarfed progeny in the second gen- eration is comparable to that of Mr. Burbank 's hybrid walnuts, in which some individuals of the second generation grew ten times as fast as others. In more recent years Mr. Burbank has hybrid- [116] IN THE VEGETABLE GARDEN ized many varieties of beans, and has found it feasible to segregate and recombine the traits of different varieties in almost any desired combina- tion. By hybridizing and selection he has been able "to put the pod of one bean on the vine of an- other," somewhat as Mendel did with his peas. He has operated with about forty varieties of beans, and has produced new combinations almost infinite in number. No plant, he says, can present greater surprises or wider diversity among the hybrid progeny. And he thinks that the bean offers as many inducements for improvement as any other plant under cultivation. It is a plant that should prove peculiarly attractive to the amateur. Many varieties of beans are available, and they may be grown readily in any corner of the vege- table garden. If you will hybridize almost any varieties that are at hand, you may be sure of interesting results next season. EXPERIMENTS WITH SWEET COEN Another plant with which you may experiment with full assurance of interesting results is the sweet corn. If you have chanced to grow in your gardens two varieties of corn, one having yellow kernels and the other white, you have probably noticed ears that were mixed, bearing partly white and partly yellow kernels. [117] LUTHER BURBANK These were the product of cross-breeding ex- periments performed for you by the wind. And had you chosen to do so you might have carried the experiments further and been witness of the application of some very fascinating prin- ciples of heredity. Now that your attention is called to it, you will do well to take the matter into your own hands and forego the assistance of the wind in the particular experiments in question. The pollen of the corn, as you doubtless know, is borne in the tassel at the top of the stalk. The pistillate flowers are borne on the stalk itself, and their presence is indicated by the putting out of the familiar wisps of so-called silk, each strand of which is in reality a pistil that leads to the egg cell, which, if fertilized, will become a kernel of corn. Under ordinary conditions the pollen sifts through the air and is dusted over the silky pistils, its germinal nucleus making its way along the substance of the tenuous pistil to the egg cell. If there are different varieties of corn growing in the same neighborhood, cross-fertilization is al- most certain to occur. In the case of most kinds of plants, cross- fertilization does not affect the appearance of the immediate fruit, but shows its effect in the plants that grow from the seed. But corn is anomalous in this regard, for the kernel shows at once the influence of the foreign pollen. If, for example, the pistils of the variety of £118] IN THE VEGETABLE GARDEN corn that ordinarily bears white kernels are fer- tilized with pollen from a yellow variety, the kernels will be yellow, because this color is "dom- inant," in the Mendelian sense. And if part of the pistils receives pollen from the yellow variety and part from the white variety, the resulting ear may be variegated, some kernels being yellow and some white. Thus you may know at once whether cross-pollenation has been effected. This obviously gives a clew to some interesting possibilities of experiment. You might, for example, apply pollen from two or three different varieties of corn to different parts of the silky tassel. You will thus secure an ear of corn that is a conglomerate of different strains of heredity. There are other qualities beside color that may be considered. For example, some varieties of corn have more starch, others more sugar. The starchy kernels are plump, the sugary kernels wrinkled when mature. Starchiness is dominant to the other condition; so the kernels fertilized by the starchy variety will be plump, in contrast to the wrinkled sugary ones. It is obvious that interesting combinations are possible if you hybridize, let us say, a variety having starchy white kernels with one having sweet yellow ones. The immediate result of this particular com- bination would be that all the kernels of an ear thus cross-pollenized would be plump and yellow. But if these kernels are planted, the crop grown [119] LUTHER BURBANK from them next season (if self -fertilized) will show interesting varieties and recombinations of the various qualities. There will be some kernels that are plump and yellow, others that are plump and white; some that are wrinkled and yellow, others that are wrinkled and white. And there is exceptional interest in the fact that these different types of kernels may appear on the same ear, and that they will exist in a predictable mathematical proportion. In accord- ance with Mendelian principles there will be three yellow kernels to one white, and three plump ones to one wrinkled. But further breeding ex- periments would show that two out of three plump kernels carry the wrinkled condition as a recessive trait, and that two out of three of the yellow ones carry whiteness as a recessive trait. This can be proved by planting the kernels and observing their progeny in another season. The experiment thus carried out will come to have the fascination of a game of chance, but un- like most games of chance, it will well repay the effort bestowed upon it. Incidentally, in the course of such an experi- ment, you will probably be able to develop new varieties of sweet corn that will meet with ap- proval on the table, at the same time that you are finding entertainment in a game at heredity in which you co-operate with nature and direct her forces. [120] MR. BURBANK'S WHITE BLACKBERRY. This remarkable variety was produced by crossbreeding and selec- tion. It is now a thoroughly fixed variety, coming true from the seed. If such a fruit were found in a state of nature it would unhes- itatingly be pronounced a distinct species. IN THE VEGETABLE GARDEN MODEKN COEN AND ITS ANCESTEY Mr. Burbank in the early day of his work as a gardener devised a method of forcing sweet corn in such a way as to bring it to market ten days or so in advance of the ordinary time of matur- ing. The method consisted of generating the seeds in the greenhouse and then planting them after they had formed roots and sprouts an inch or more in length. No attention was paid to the way in which the little plants fell into the drills or fur- rows in which they were planted. They were simply dropped in as kernels of corn would be dropped, and covered with a thin layer of soil. Sometimes they continued to grow so rapidly that they would be found pressing through the soil the next morning; and this start caused the plant to outstrip others that were grown from the seed in the ordinary way. In recent years Mr. Burbank has experimented very extensively with corn, in particular with the primitive type known as teosinte, a giant form of grass indigenous to Mexico. This plant bears a head that is more like a head of wheat than like an ear of corn. But by selective breeding and hybridization Mr. Burbank has been able to pro- duce all gradations between this primitive type of corn and the familiar cultivated varieties. He has thus virtually demonstrated that the culti- vated corn is descended from teosinte. It is possible by selective breeding to increase the size of the cornstalk, and to cause the ears to [121] LUTHER BURBANK be borne at any desired height from the ground. Mr. Burbank has developed a variety of corn, for example, that bears its ears at such a height that a man can scarcely reach them. Such a .variety has no commercial value, but was developed for its scientific interest. You may amuse yourself by developing from the same stalk a variety of corn bearing the ears at the height of five or six feet and another variety bearing them only a foot from the ground. Such a series of experiments has been carried out suc- cessfully by the Agricultural Experiment Station of Minnesota. It is possible also to modify the chemical composition of the corn, increasing or decreasing its protein content. Such experiments, aside from their possible practical value, have a high degree of interest, and they fall readily within the scope of the operations of the amateur who has even the small- est garden at his disposal. Another interesting variation has to do with color of leaf of the corn plant. By selective breed- ing, Mr. Burbank has produced a variety called rainbow corn because of the striping of the leaves. He now contemplates combining this with sweet corn of good quality, so that the plant may com- bine ornamental quality with practical utility. COMBINING POTATO AND TOMATO Experiments of a totally different kind that may lead to even more fascinating results may be per- [122] IN THE VEGETABLE GARDEN formed with the potato and the tomato, along the lines of an experiment first made a good many years ago by Mr. Burbank. This consists of grafting the stem of the tomato plant on the roots of the potato, and, contrariwise, the stem of the potato on the roots of the tomato. The process of grafting is not unlike that of grafting twigs on a tree, consisting essentially of bringing the cut surfaces of the two stems in close and accurate contact, and binding them together until union is effected. The stems should be of the same size, and it will be well to notch them in such a way that they fit accurately together. The experiment will not be successful in every case, but the interesting results of a single success will compensate for many failures. In Mr. Burbank 's experiments the potatoes grown on vines having tomato tops were curi- ously distorted in shape, and some of them had a rough and scaly surface. The leaves of the to- mato were seemingly not able to produce just the right kind of material for the manufacture of normal potatoes, yet they performed their vicari- ous function better than might have been expected, considering that under normal conditions they are called on to produce material for something so widely different from the potato as the familiar fruit of the tomato. Perhaps it should be explained that the leaf of a plant contains the laboratory in which carbonic acid from the atmosphere is compounded with water to form the organic sugars and starches [123] LUTHER BURBANK that are the original basis for the building of living matter. The starch of the potato is not manufactured in the ground, but in the leaf of the potato vine, whence it is transmitted in the form of a soluble sugar to the root, and there transformed into starch and deposit in the tuber. This must be understood if one would appre- ciate the unwonted task to which the tomato tops were called when they found themselves joined to the stem of a potato plant. When the combination was made the other way, the tomato roots proved unable to develop the capacity to form tubers, but the potato tops re- tained their tendency to develop material for the manufacture of tubers. So a compromise was effected by growing the potato not underground on the roots of the to- mato, but in the air, from the axils of the leaves of the potato plant. A potato vine grafted on tomato roots and decorated with aerial potatoes is surely an anom- aly that would excite interest in any garden. Mr. Burbank has shown us how to produce this anomaly, and there is no reason why the experi- ment should not be repeated. It is true that no permanent vegetable of value has been developed in this way, but the experiment has interest that fully justifies it, quite aside from any question of practicality. It is possible, moreover, that plants thus grafted might be more susceptible of hybridization, and that a new and important vegetable might be pro- [124] IN THE VEGETABLE GARDEN duced by hybridizing the flowers of the potato and tomato. Hitherto Mr. Burbank has been un- able to effect this hybridization, although he has many times attempted it. But he is foremost to proclaim that such negative experiments are never final. The case of the sunberry — produced after twenty-five years of fruitless effort — among others taught him that one may succeed at last in hybridizing two species that have refused to unite in thousands of earlier experiments. It is well known that as a rule plants that cannot be hy- bridized cannot be successfully grafted. So the fact that potato and tomato may be grafted is in itself evidence of the probable feasibility of hy- bridizing the two under proper conditions. Any amateur may raise a few tomato vines and a few potatoes and the transfer of pollen from one to the other may readily be effected. Should fertilization result, the hybrid combining the strains of the potatb and tomato is sure to be a plant of exceptional interest, and not unlikely it will prove a valuable addition to the list of garden vegetables. At all events, the attempt to effect this hybridization is worth half an hour of your time. If you were to succeed where Mr. Burbank has failed, your feat would indeed be worth recording. Even though you fail of your main purpose, the effort will at least afford you an interesting study in the anatomy of flowers. [125] LUTHER BURBANK VAEIED OPPORTUNITIES The foregoing instances will serve to guide you in experiments that may be applied to all the re- maining products of the vegetable garden. Whatever the vegetable to which you pay atten- tion, you will discover that there is a considerable range of variation among different specimens of the same variety. By selecting for seed purposes the specimens that present in the fullest measure the quality that you desire to accentuate, you will at once be on the track of the development of new and improved varieties. If in any case you find that the plants do not vary in the direction in which you think there might be improvement, you may adopt the expedi- ent of cross-pollenizing the flowers, uniting dif- ferent varieties of the same species or individuals of closely related species. You may, for example, cross-fertilize different varieties of onions, or you may hybridize the onion with the leek or the chive. Mr. Burbank has produced numberless new varieties of the onion family by hybridizing its different members. Some of these have beautiful blossoms, and some have bulbs of extraordinary size. The Burbank pink chive, for example, is a decorative border flower as well as a palatable table vegetable. And there are beds of his hybrid onions that take fairly high rank in the flower garden. Meantime he has developed varieties of the [126] IN THE VEGETABLE GARDEN Spanish onion with bulbs weighing three or four pounds. He states that the various members of this family are easy to work with by way of selection, and that the only difficulty in hybridizing them is due to their small flowers, and may readily be overcome by the use of reasonable care. Whether by hybridizing or by mere selection, he says, the onion is susceptible of great improvement along various lines, — size, flavor, decrease of odor, — and the ease with which it may be cultivated especially commends it to the amateur. In recent years Mr. Burbank has made ex- tensive experiments in developing the artichoke, a vegetable that is exceedingly popular in Europe, but which until recently has been somewhat neg- lected in America. The artichoke is a composite flower; that is to say, it belongs to the family of which the sunflower furnishes the type, and which is characterized by growing a large number of flowers in a single head, surrounded by a row of petal-like rays. In cross-fertilizing flowers of this type, Mr. Burbank is accustomed to wash away the pollen with a stream of water from a garden hose before applying the head of another flower and rubbing the two flower heads gently together to effect pollenization. The part of the artichoke that is eaten is the flower head itself, the protecting bracts of which have developed a pulpy portion at their base. The receptacle on which the flowers grow, known as the heart of the artichoke, is also edible. But the [127] LUTHER BURBANK flower must be plucked before it opens, as it is inedible after coming to maturity. By crossing various varieties of the European artichoke, and by selective breeding, Mr. Burbank has developed new varieties that are exceedingly large, the flower heads being more than two feet in circumference when open. The mature flower, with its mass of blue flurries, is so attractive that it is sometimes allowed to open and picked for ornamental purposes. The artichoke has been so little worked with that it offers good opportunities for the amateur, either through cross-breeding or merely through selection. Plants grown from the seed are sure to show a certain range of variation, and you may readily develop improved varieties by select- ing seeds from the best and repeating the selection through two or three successive generations. Parsley, the mints, the mustards, cabbages, turnips, peppers — all of these have been worked with extensively by Mr. Burbank, and all have pos- sibilities of development that make them attractive for the amateur. Another vegetable with which one of Mr. Bur- bank's greatest triumphs has been effected is the winter rhubarb, which came from New Zealand with a stem scarcely larger than a lead pencil, but which has now been developed until it is of gigantic size, and which has taken on the habit of perpetual bearing. The latter habit is ex- plained, in part at least, by the fact that the rhubarb came from another hemisphere. Summer [128] IN THE VEGETABLE GARDEN in New Zealand is of course our winter time, and vice versa, and the plant found it difficult to adjust itself to the new order of seasons. By encourag- ing it to maintain its old system of reckoning in the new latitude, Mr. Burbank made it practically a perpetual bearer. It is at its best in the win- ter season, when ordinarily rhubarb is altogether dormant. Another important line of experiment to which Mr. Burbank has devoted much time and atten- tion has to do with the introduction of new races of garden vegetables. He has worked with a species of lily called the camassia, which bears beautiful flowers, until its bulb gives promise of rivaling the potato. He is similarly educating another lily called the brodiaea; and yet another known as the tigridia — a bearer of beautiful flow- ers; and he has even turned attention to such hitherto unwelcome plants as the dandelion, the thistle, and the burdock, all of which he believes are likely candidates for admission to the vege- table garden. The bulb of the tigridia is regarded by Mr. Bur- bank as the most delicious of vegetables when cooked. Sundry tropical solanums — relatives of the po- tato and tomato — are being relieved of their spines and educated to bear better fruits by Mr. Burbank. The ground cherry and the passion flower are other plants that he has in training, the fruits of which have already made significant progress. In the further development of these [129] LUTHER BURBANK plants, and a good many others, any amateur who chooses to master the technique of plant experi- mentation may take a hand, and there are few fields that offer better opportunities for the em- ployment of leisure half-hours. Viewed in this light, the vegetable garden be- comes a maze of fascinating and beckoning mys- teries. [130] CHAPTEE VII BURBANK IN THE FLOWER GARDEN THIS chapter describes Mr. Burbank's method of mating the flowers with an eye to the production of new varieties, and the methods of selective breeding through which the colors and forms of blossoms may be developed. Almost any flower may be improved in size, changed in form, made double, or altered in color. Mr. Burbank has made hundreds of such modifica- tions in the case of flowers from all parts of the world, including both the common garden varie- ties and the rarest exotics. The exact method by which these changes are wrought is here described, — how, for example, the Shasta daisy was developed, the scented calla, the blue poppy, the crimson eschscholtzia, and numerous others. Typical illustrations are given as to each of the different methods of procedure, and the entire process is so clearly described that the amateur may produce similar results if he will intelligently follow the directions given. You may have flowers different from those of your neighbor, and, indeed, different from any that have ever been seen before, if you are willing to take the trouble to develop them. And it will appear that in many cases new developments may [131] LUTHER BURBANK be brought forth rapidly. In dealing with flowers, you are not required to wait for a term of years, as you sometimes would be in developing new races of orchard fruits. For this reason, and also because of the great variety of interests that at- tach to flowers, the amateur may very well begin his experiments in the flower garden. In undertaking the improvement of a flower, one may have in mind the form of the blossom, its size, profusion of bearing, color, or odor. Mr. Burbank 's work furnishes almost countless illus- trations of improvement in regard to all of these qualities, sometimes singly, sometimes in com- bination. Of course the simplest type of experiment is that in which a single quality is under considera- tion. Such a case as that of Mr. Burbank's scented calla furnishes a typical illustration. The calla, as everyone knows, is ordinarily quite without a pleasing fragrance; if it has any odor at all it is a slightly disagreeable one. But the variety of calla developed by Mr. Burbank and introduced under the name of Fragrance has a delicious perfume that adds very greatly to the attractiveness of this beautiful flower, and Mr. Burbank tells us that this quality of fragrance was developed in the calla in the course of three generations of selective breeding, without hy- bridization. [132] IN THE FLOWER GARDEN WHY FLOWEES HAVE PEKFUME Most readers are probably aware that — accord- ing to accepted theory — the perfume of flowers in general has been developed through natural se- lection as an aid in attracting insects, on which the plant depends for cross-fertilization. We human beings have come to enjoy the fragrance of the rose and the apple blossom, and we are some- times egotistical enough to suppose that these perfumes were developed for our delectation. But the botanist assures us that, so far as the wild flowers are concerned, man's tastes were not in the least consulted in the development of either color or fragrance. The development of scented and beautiful flow- ers was the work of sundry insects, of which the bee is most important. The colored petals of the flower and the perfume that it exhales are adver- tisements addressed to the bee, intended to guide him to the nectary within the tube of the flower, in approaching which the insect will unconsciously come in contact with the pollen-bearing stamens, and in due course transfer the pollen from one flower to another. When, therefore, we find a flower like the calla that is devoid of fragrance, we may feel pretty certain that this flower is not habitually fertilized by the bee, but depends upon some other agency. In the case of the calla, the agents that effect cross-fertilization are sundry small gnats and flies that find the tubular canopy a welcome shelter [133] LUTHER BURBANK at night. This white canopy is really a modified leaf and is called by the botanist a spathe. The essential organs of the flower are distributed on the central column called a spadix, and are ex- ceedingly inconspicuous. The upper portion of the spadix bears the pollen, and the lower portion is the pistillate surface. But the two parts do not mature at the same time, so self-fertilization does not take place as would otherwise be in- evitable. It has been found by experiment that the air inside the tubular spathe is somewhat warmer than the outside air. So it is not strange that insects should gather here, and they naturally come in contact with the pollen, and carry it to other flowers that they subsequently visit. The whiteness of the calla suggests that it is designed to attract night-roving insects, the white flower being more conspicuous at night than a brightly colored one. MAKING A FBAGEANT CALLA It is not unlikely that some ancestors of the calla depended on the bee for cross-fertilization, and hence were fragrant. Otherwise it is hard to account for the appearance in Mr. Burbank's colony of callas of an individual that had a faint but appreciable perfume. Whatever the explanation, such an anomaly did appear a good many years ago, and Mr. Burbank detected its presence and at once decided that this [ 134 ] IN THE FLOWER GARDEN flower was worthy of cultivation. He carefully saved the seed of this individual, and watched the development of the progeny with solicitude. Most of them were quite odorless. But there were a few that reproduced the fragrance of their parent, and one of these was more distinctly fragrant than the original. The seeds of this specimen were saved in turn, and among the plants that grew from them were several that were distinctly fragrant, and, as be- fore, one that conspicuously excelled the others. Indeed, the perfume had now been so accentuated that this individual was as fragrant as could be desired. The plant was propagated by dividing the roots, after the usual method, and soon a com- pany of callas was produced, all of which dupli- cated the qualities of the parent form. This was the flower that was sent out under the name of Fragrance. The process of development of the scented calla, then, consisted in raising seedlings from an indi- vidual that showed a trace of perfume and select- ing in turn through successive generations the individual that had inherited this quality in largest measure. But the most interesting feature of the experi- ment was the fact that the quality, although not transmitted to most of the progeny, was accentu- ated in the case of the individual to which it was transmitted. And this, fortunately, is typical. Wherever a flower shows a peculiarity that differentiates it [135] LUTHER BURBANK from its fellows, this peculiarity may be accentu- ated or exaggerated by selective breeding. And sometimes the development is gratifyingly rapid. NEW COLOES IN THE POPPY As another illustration of this, take the case of Mr. Burbank's crimson California poppy, named by the botanist Eschscholtzia. This flower in its wild state is of a brilliant orange color, but one day Mr. Burbank discovered a specimen that showed a thin line of crimson run- ning up the center of one petal. The seeds of this poppy were carefully preserved, and among the plants that grew from them one was discovered that had a flower with a slightly wider line of crimson. The next generation showed farther progress in the same direction, and presently a poppy had been produced the petals of which were crimson throughout. There was no necessity for hybridization or for? any directive manipulation. All that was necessary was to preserve and sow the seed of the plant that showed the tendency to vary, and thus to give the new color an opportunity to assert itself. In this case the crimson color appeared, as just related, as a narrow but conspicuous line. There are other cases in which a new color appears only as a modified tone, readily overlooked by the casual observer. Such a case was that of the [136] INSPECTING HYBRID BLACKBERRIES Mr. Burbank (at the right) is discussing with Dr. Williams the results of an experiment in crossing the thornless blackberry with various other selected varieties. IN THE FLOWER GARDEN flower from which Mr. Burbank developed his celebrated blue poppy. The flower that showed the original tendency to variation was a Shirley poppy, the red color of which lacked a little of its usual beauty. To Mr. Burbank 's discerning eye there seemed a certain smokiness of hue that suggested possibilities of variation. So of course the seeds of this poppy were carefully preserved. In the next generation there were a few individuals that showed a more conspicuous smokiness of color ; and in the course of three or four more generations individuals appeared that had flowers distinctly bluish in hue. This bluish quality was further accentuated in succeeding generations, until a poppy appeared that was of a clear pale-blue color. There is no record that anyone ever saw a pure blue poppy before, yet the materials for blue pig- mentation were evidently hidden in the germ- plasm of the poppy, and selective breeding re- moved the obscuring elements and enabled the blue color to make itself manifest. The principles of selective breeding employed were simple to the last degree ; yet through their application a flower was produced that is marvelously transformed. Another curious and interesting color modifi- cation was effected in Mr. Burbank 's ^silver- lining" poppy. The original flower was crimson with a black center. A specimen appeared that showed a white line between the black center and the crimson petal. By selective breeding this line was widened generation after generation, until [137] LUTHER BURBANK the flower was white with black center ; the white extending just over the outer edge of the poppy, the rest of the backs of the petals remaining crimson. CHANGING A LEAP It is not the' blossom alone that may thus be modified by selective breeding. Other parts of the plant may be similarly transformed. A strik- ing illustration of this is furnished by a leaf modification that Mr. Burbank brought about in the case of the California plant sometimes called "wild geranium," known to the botanist as heuchera. This plant usually has a fairly smooth leaf with an indented edge, not unlike that of the ordinary cultivated geranium. But Mr. Burbank once chanced upon a specimen growing wild that showed a tendency to crinkling of the edge of the leaf. He transferred this plant to his garden, saved its seed, and searched among the progeny for an individual that reproduced the anomaly of leaf formation. As expected, some individuals were found that not only reproduced but accentuated the anomaly. And in succeeding generations in- dividuals appeared in which the peculiarity was so accentuated that ultimately the leaf became crinkled and crenated over practically its entire surface, losing all resemblance to the normal form and appearance. The plant that showed this peculiarity resem- [138] IN THE FLOWER GARDEN bled the wild parent form as to blossom and gen- eral habit. But its leaves were so modified as to constitute a new variety to which a specific name has been given. Hundreds of other instances might be cited in which Mr. Burbank has modified the quality of stem or leaf or flower of a familiar or unfamiliar plant by this process of selective breeding, in which a " spontaneous " tendency to variation sup- plied the material with which the experimenter worked. It is rare indeed for a plant to come under his observation in which he does not detect some indication of what to his keen perception seems a bid for improvement. If you will carefully examine any group of flowers in your garden, you will at once see that no two plants of the same variety are precisely alike ; and if you wish to accentuate any observed variation, you may undertake the task with full confidence, if you will follow out the method just outlined. In some cases progress will be rapid, in others slow, but you are almost certain to see some improvement among the progeny of the first generation, and not unfrequently you may detect a very marked transformation in size or form or color, or in any other quality for which you are selecting, in the course of two or three genera- tions. The fact appears to be that every individual plant is the center of many conflicting hereditary currents. Selective breeding singles out a tend- ency and gives it an opportunity to manifest its [139] LUTHER BURBANK possibilities. By this method alone you may de- velop any number of new varieties of flowers in your garden with an insignificant expenditure of time and effort. All that is necessary is clearly to grasp the principle of selective breeding, and to search dili- gently in each successive generation for the indi- vidual that shows the strongest tendency to vary in the desired direction. CONSTEUCTING A NEW SPECIES But while remarkable transformations may thus be effected by mere selective breeding, it will be understood, of course, that with the flowering plants, as with fruits and vegetables, it may often be desirable to give an added stimulus to varia- tion through the hybridizing of different species, or the crossing of marked varieties. Indeed, this is the usual method through which striking new varieties have all along been developed in Mr. Burbank's garden. Even where selective breed- ing, along the lines thus described, is used to ac- centuate or fix a variation, there has very com- monly been a preliminary series of experiments in which variation has been stimulated through hybridization. Mr. Burbank early discovered that new varie- ties may be produced by this method, and the per- sistent application of the method to countless species of plants laid the foundation for his con- spicuous successes. Beautiful ixias, for example, [140] IN THE FLOWER GARDEN were thus developed, and marvelous hollyhocks; also new races of tritonias, and numberless new and extraordinary varieties of starflowers, lilies, watsonias, petunias, larkspurs, marigolds, sun- flowers, and scores of others. As a typical illustration of what he has been able to accomplish in this field, we may cite the case of the Shasta daisy. This remarkable flower has for one of its an- cestors the little ox-eye daisy familiar everywhere throughout the eastern United States. This flower was hybridized with the European daisy, the strains of two subspecies or marked varieties being introduced. Selective breeding among these hybrids produced a flower that was much larger than either of the parent forms and in many ways more graceful and beautiful. But the flower was not of as pure a white as Mr. Burbank desired, and to improve it in this regard, as well as to give it fresh tendency to variation, he crossed the hybrid form with a Japanese daisy that had a small flower of dazzling whiteness. The progeny showed the expected tendency to variation, and some of them combined the whiteness of the Japanese parent with the large size and attractive qualities of the American-European hybrid. By selective breed- ing numerous new types were developed, some of them bearing flowers not far from six inches in diameter. The new flower that thus combined the racial strains of three species was itself so different [141] LUTHER BURBANK from any one of the parent forms that it would be regarded by any botanist who found it in the wild state as a unique species. It is, in short, a new species of daisy created by artificial selection under the hand of the plant developer. It was named the Shasta daisy. Various series of experiments in selective breeding have developed numerous varieties of Shastas, some having broad flat ray flowers, others thin and fimbriated or tubular ones, yet others being partially double. In a word, the Shasta daisy is not only a new form of flower, but one that has developed numberless varieties, comparable, therefore, with various other types of cultivated flowers. Yet there was no such thing as a Shasta daisy in existence until Mr. Burbank combined the different species from Europe, America, and Japan, and thus gave opportunity for the blending of hereditary factors that had their origin in the environing conditions of three continents. The case of the Shasta daisy, then, may be taken as typifying the second of the two impor- tant methods through which the plant developer operates, — the method of hybridization. Of course the perfected Shasta represents also the use of the other method, that of selective breeding. Indeed, the two methods go hand in hand, each supplementing the other. Taken to- gether, they constitute the basis of a complete method of plant development, and through their application all the possible transformations that [142] IN THE FLOWER GARDEN may be brought about in a limited period of time may be effected. QUANTITY PRODUCTION Of course your task will be facilitated if you raise large numbers of individual plants. Part of Mr. Burbank's phenomenal success is due to the scale on which he operates. He raises indi- viduals of a given variety not merely by thou- sands, but by hundreds of thousands or millions. Nor is a large territory required for these opera- tions, particularly in the case of flowering plants, because great numbers of these can be raised in a plot a few feet square, and only the most satis- factory specimens are preserved in each succeed- ing generation. As an instance of the rigorous selection through which Mr. Burbank's flowers are improved, it may be related that on one occasion he destroyed eight cords of bulbs of the South African plant called the watsonia, preserving only a few specimens that were the superlative ones among the hun- dreds of thousands. It may be asked why Mr. Burbank destroys these bulbs, when he might readily sell them. The answer is that the bulbs represent an inter- mediate stage of development, and as has been pointed out in another connection, if they were allowed to go out they would be advertised presently by some unscrupulous person in a way to mislead the public and do injustice to the [143] LUTHER BURBANK plant developer himself. Mr. Burbank never allows a new plant creation of any kind to be in- troduced unless lie is thoroughly convinced that it is equal in all respects to any similar variety already on the market, and superior in at least one respect. Until the new variety can meet this test, it is still in the experimental stage, and only a few of the most promising specimens are pre- served, the others being ruthlessly sent to the bonfire. To the observer who sees hundreds of thousands of the plants bearing really beautiful flowers thus destroyed each year at Santa Rosa and Sebas- topol the method seems ruthless; but it is an inevitable concomitant of the comprehensive plan through which so many wonderful varieties of flowers, vegetables, and fruits have been devel- oped in Mr. Burbank ?s experiment gardens. Among the most interesting of the plant colonies that have been produced in countless galaxies to supply Mr. Burbank with material for selection are such familiar flowers as the lilies and poppies. HALF A MILLION NEW LILIES Mr. Burbank 's experiments with lilies were car- ried out on a most comprehensive scale for many years. He hybridized all the exotic species and varieties that seemed to promise favorable results, until he had the most extraordinary collection of lilies, doubtless, that ever existed anywhere in the world, — "here a plant six feet high with yellow [144] IN THE FLOWER GARDEN flowers beside one only six inches high with dark red flowers, and farther on one of pale straw or snowy white or with curious dots and shadings; some deliciously fragrant, others faintly so ; some with upright, others with nodding flowers; some with dark-green woolly leaves or whorls or with polished, light-green, lance-like scattered leaves." In one of his early announcements, Mr. Bur- bank spoke of having "half a million kinds of lilies yet to unfold their petals for the first time," adding that he was still planting from one to three pounds of hybridized lily seed every season. "Search this earth all over," he said, "climb every mountain, plunge into every canon, valley, and jungle ; and, when all this is done, visit every park, garden, nursery, and conservatory ; go any- where, everywhere, and as many varieties of charming lilies cannot be found as I have pro- duced. All the earth is not adorned with so many new ones as are growing at my establishment." It was pointed out that these hybrid lilies were crosses of parents selected for health, hardiness, easy management, and rapid multiplication, as well as for fragrance, beauty of coloring, grace, and abundance of flowers; and the justifiable as- sertion was made that "in these hybrids a broad foundation has been laid for endless varieties which will reward lovers of flowers for ages to come." A glance at the photographic reproductions that accompanied the announcement justified the plant developer's enthusiasm. [145] LUTHER BURBANK STBANGE HYBEID POPPIES As to the poppies, the results of hybridizing in Mr. Burbank's hands have been no less ex- traordinary. Some of his most interesting results have attended the crossing of the opium poppy with sundry varieties of the Oriental poppy. Rather curiously he found that the pollen of the opium poppy was ineffective when used on the Oriental, yet when the reciprocal cross was made, the pollen of the Oriental being used on the opium poppy, seed was produced, and a great number of hybrids were soon under observation. The hybrid colony comprised more than thirty thousand plants, including many extraordinary forms. For example, the hybrid poppies some- times produced enormous seed capsules, five or six times as large as the ordinary seed capsule of either parent. Yet in other plants the seed capsule would be small ; in still others twin cap- sules were produced; and with numerous others there was not even the intimation of a capsule, the flowering stem ending abruptly like the end of a lead pencil. And even where the capsule was large, the seeds were produced in much dimin- ished quantity, and were shriveled and shrunken in size. The plants grown from these seeds — second- generation hybrids — were extraordinarily vari- able. Mr. Burbank declares that he has seldom seen a more remarkable company of plants. "The diversity was so great that it might be said [146] IN THE FLOWER GARDEN there were no two plants among the thousands that were even approximately identical." The foliage in particular was amazingly varied. There were long, smooth, strap-shaped leaves, and short stubby ones; smooth, glossy leaves, and rough, hairy ones; leaves like those of one or the other of the parent forms; and nondescript leaves that variously suggested the primrose, cherry, dock, wormwood, dandelion, and scores of others. The blossoms were not only diversified in color, and some of them enormously increased in size, but they showed a curious modification, in that they were produced at all seasons instead of only for a short period, as is the habit with the parent species. The first-generation hybrids themselves were perennial plants (although their mother plant was an annual), and they bloomed persistently. " There is not a day in the year when some of these hybrids are not in bloom at Sebastopol, spring, summer, autumn, or winter — blossoms can always be gathered in quantity from them. ' ' It is of peculiar interest to note that the second- generation hybrids were in part annuals, like one of their grandparents, and in part perennials, like the other grandparent. The annual and perennial habit appear to be a pair of Mendelian unit char- acters of which the perennial habit was "dom- inant" and the annual habit "recessive"; there being a characteristic segregation in the second generation. [147] LUTHER BURBANK The possibility of producing almost endless numbers of new varieties of poppies from such a conglomerate company is obvious. The difficulties are greater than might appear, however, because of the tendency to sterility. Many hybrids show greatly increased fecundity, but with these pop- pies this is reversed, the reason being, perhaps, that the plants are almost at the limits of affinity, beyond which cross-fertilization would be im- possible. THE OKIGIN OF SPECIES It should be understood that hybridization and selection are natural methods, and that in using them man is merely imitating on a small scale the practice by which nature has brought about the evolution of all the existing forms of plant and animal life. Plants in the state of nature are frequently hybridized through the agency of in- sects, or by the wind in the case of those who do not depend upon insects for cross-pollenation. Mr. Burbank cites numerous instances of nat- ural hybrids that he has observed; for example, the madia plant, or tarweed, two species of which frequently hybridize; mints of various species; the wild raspberry; and the different species of hickory nut. He believes that such natural hybrids afford the material from which new species are constantly being developed through natural selection, and the results achieved by Mr. Burbank himself in the [148] IN THE FLOWER GARDEN development of new species by this method go far to substantiate his belief. He habitually hybrid- izes species, and develops new races by artificial selection. About the only difference between this method and nature's method is that in the wild state the characteristics that are likely to be preserved through natural selection are those that are ad- vantageous to the individual plant that manifests them; whereas under conditions of artificial se- lection the plant developer considers not the needs of the individual plant, but the tastes and needs of men. Perfume is developed in Mr. Burbank's calla, for example, and in his fragrant petunias and verbenas, not because this is of advantage to the plants themselves, but because the perfume is pleasing to human nostrils. Similarly the blue color of the poppy is to please the human eye, the crinkled leaf of the geranium to satisfy a human taste for the bizarre, and the varied forms of the Shasta daisy to gratify esthetic human sensi- bilities. Natural selection would have eliminated rather than preserved the variations in question ; but civ- ilized man creates a new environment and molds the forms of vegetable and animal life to fit that environment. The results are different because the conditions are different. But the principles of development are the same, and it may fairly be said that the plant developer in applying the method of hybridization and artificial selection is [149] LUTHER BURBANK duplicating nature's method, and illustrating on a small scale the principles of evolution through which all living organisms have been developed. In making practical application of these meth- ods in the flower garden, you may select whatever plants are found there, almost at random. There is no race of cultivated flowers that does not offer opportunities for improvement through hybridiza- tion and selection. Of course you must work, in any given experiment, with species that are not too widely separated; otherwise your efforts at hybridization will be futile. You cannot hope, for example, to hybridize a rose and a dahlia. But you may hybridize the different species of roses among themselves or one dahlia with an- other, and in either case you will be fairly certain to produce forms that are different in some regard from the parent forms, offering opportunity for further improvement by selection. But although, as a rule, plants cannot be hy- bridized unless somewhat closely related, experi- ment may reveal unexpected affinities, even be- tween species belonging to different genera. Mr. Burbank has made a large number of very wide crosses, some of which have already been referred to. The interesting hybrid between the tobacco and the petunia may be recalled as an instance in point. The curious plants that resulted from this union were some of them of upright growth like the to- bacco, others of trailing habit like the petunia. It was said of them facetiously that they were [150] IN THE FLOWER GARDEN petunias that had acquired the tobacco habit. Un- fortunately they seemed incapable of forming a good root system and hence they lacked vitality. Mr. Burbank has since regretted that he did not graft them on tobacco roots, as in that way they might perhaps have been preserved. It would be well worth while for someone to try the experiment over again, carrying out this sug- gestion. / ^\ PRODUCING AND FIXING NEW VARIETIES It will be recalled that Darwin based his cele- brated hypothesis of natural selection on the ob- served fact that plants and animals in a state of nature vary. He spoke of this variation as "spontaneous," thereby confessedly begging the question. Mr. Burbank believes that in a large number of cases such "spontaneous" variation is in reality due to hybridization. In the same way he explains the occurrence of those variations which, because of their wide departure from the parent form, have been described as "mutants." The case of the mutants was brought prom- inently to the attention of the biological world a few years ago by Professor Hugo De Vries, the celebrated Amsterdam botanist. His observations were chiefly made with the evening primrose, and he founded on these observations the theory of evolution by mutation, — that is, by sudden vaults, — as a modification of the theory of evolution by the accumulation of minute changes. [151] LUTHER BURBANK Professor De Vries was unable to explain the cause of the mutation; but Mr. Burbank at once declared his belief that the celebrated evening primrose with which Professor De Vries had worked was really a hybrid, and this explanation is now coming to be pretty generally accepted. Certain it is that Mr. Burbank has produced mutants without number in the course of his ex- periments through the process of hybridization, — a mutant being described as a form that departs radically from the type of its seed parent. The particular mutants that first attracted the atten- tion of Professor De Vries bred true to the new type from seed, thus seeming to constitute a new race. The same thing is true of many of the mutants that Mr. Burbank has produced by hy- bridization. But as to this point, there is oppor- tunity for diversity of habit. A new form pro- duced by hybridization may breed true, as in the case of Mr. Burbank 's Primus berry, but it is much more likely, as we have seen illustrated, to show a great diversity of form among its imme- diate progeny. Some of these forms may breed true, while others will fail to do so. This is of the utmost importance to the plant developer, particularly in the case of annual plants that must be grown from seed. In the case of plants that can be reproduced by division the matter is not so important, as any new variety developed may be propagated indefinitely without use of the seed. Such is the regular method of propagation, as we have seen, in the case of the [152] MR. BURBANK INSPECTING GARLIC SEEDLINGS The plants are specially cross-bred and selected specimens, having peculiar qualities of thrifty growth, as well as exceptional flavor. IN THE FLOWER GARDEN orchard fruits, of such vegetables as the potato, and of bulbous plants in general. But a large number of our flowering plants are annuals that are reproduced solely by the seed. With these it is obviously a matter of great im- portance that the seedlings should reproduce the qualities of the parent, otherwise the new variety that you produce would have no permanency. It is precisely here that the patience of the plant developer is most often put to a test. Very generally the new variety that you develop by hybridization, and which you would wish to per- petuate, does not breed true from the seed. It becomes necessary, then, in order that your new variety shall have real importance, that you should practice systematic selective line breeding until you "fix" the desired quality or qualities. To this end, you must sow the seed of your se- lected variety, and permit all the seedlings to ma- ture. Among the hundreds of plants, there will probably be a few that reproduce the attractive qualities of the parent. The best of these should be carefully inbred — self-fertilized — and its seed sown next season ; and a similar selection followed up, year after year, if need be, until a plant is secured all the seed of which will reproduce the desired quality. If a single quality is in question, you will gen- erally be able to "fix" the type in two genera- tions. But if several new qualities are combined in your favored variety, it may be necessary to carry out the selective line breeding for five or [153] LUTHER BURBANK six generations. Much depends on whether the qualities under observation act as " dominant " or as " recessive" qualities in the Mendelian sense. The exact meaning of this and the manner of test- ing have already been explained, and will be further elaborated in another connection. The prime essential, however, is that the plants shall be rigidly guarded against cross-fertiliza- tion. New varieties are created by cross-polleniz- ing ; they are fixed by self-pollenizing. In a care- fully conducted experiment, it will be well to cover the plant with a net, to keep the bees from inter- fering, meantime hand-pollenizing each blossom with pollen from other flowers of the same plant. METHODS OF POLLENIZING In order to carry out this all-important business of pollenizing (cross-breeding in some cases, in- breeding in others), it will obviously be necessary to study the anatomical structure of different flowers. The principle is always the same — pollen from one flower is to be carried to the pistil of another. But some flowers have the stamens ar- ranged in a peculiar way, and the casual inspector may not at first glance recognize them. Plants of the iris tribe, for example, have a peculiar mechanism whereby the pollen is de- posited on the back of a bee, and then is scraped off by the pistil of the next flower that the bee visits. The amateur botanist might not at first glance recognize the pistil, and hence might be [154] IN THE FLOWER GARDEN puzzled as to the way in which pollenation is to be effected. Again, the milkweed has its pollen in sacks ar- ranged like saddle-bags, designed to entangle the legs of the bee, and the amateur might not recog- nize them as bearers of pollen. A little study of the mechanism of the different flowers with the aid of a magnify ing-glass will solve all of these difficulties. Meantime the insight that will thus be gained into the curious modifications of structure through which nature guards against the self- fertilization of the flower will prove a source of perennial interest. Theoretical botany and prac- tical plant development go hand in hand, and the flower garden is the ideal place to make initial studies of one and practical tests of the other. [155] CHAPTER VIII THEORY AND PRACTICE I HAVE all along attempted to make it clear that the fundamental principles of plant breeding are simple, and that the amateur may begin experiments and even carry them to interesting conclusions with comparative ease. It is desirable now to supplement what has previ- ously been said by calling attention to some of the complications that are sure to arise as the work of plant breeding progresses ; and in so doing, of course, to point out clearly how these complica- tions may be met. Let us first recall what has been outlined in the previous articles as to Mendelian heredity. We saw that when the flower of a tall pea vine is fertilized with pollen from the flower of a short pea vine the progeny will all be tall; but that in the second generation one vine in four will be short, like one of the grandparents. Thus in the vine of the first filial generation the hereditary factors for tallness may be said to be " dominant, " since they make themselves manifest, and the factors for shortness may be said to be "re- cessive," since they are submerged and for the time being inoperative. But these recessive fac- tors come to the surface, as it were, in one in [156] THEORY AND PRACTICE four, on the average, of the progeny of the next generation. And it is observed that the short vine in which the recessive factor thus again makes itself manifest will breed true to shortness, the factors for tallness apparently being altogether eliminated from its germ-plasm. Meantime, as just noted, for every short vine of this second filial generation there are three tall ones; and further breeding tests will show that, while these three vines look just alike, there are fundamental differences in their germ-plasm ; for one of them will breed true to tallness (being a pure dominant, as the saying is), while the other two are " mixed dominants" and will have progeny of which, in each group of four, one will be short (pure recessive), one tall (pure dom- inant), and two also tall but of mixed germ-plasm like their parents. The essential point is simply that any char- acter that acts as recessive in the Mendelian sense will be seemingly eliminated in the first-genera- tion cross that brings it in combination with the opposite character; but that the recessive char- acter will reappear in the next generation, and will then breed true. So when you find that you are dealing with a recessive quality, you may fix it in the third generation without difficulty. But the dominant quality, on the other hand, although it makes itself manifest in all the first-generation progeny, and in three out of four of the second- generation progeny, has to meet the masked rivalry of recessive factors in two out of three [157] LUTHER BURBANK of its second-generation members, so that these cannot breed true. When you wish to fix a dominant quality, there- fore, you must save the seed of each individual and plant it in separate plots. Only in this way can you determine which individual is a pure dominant, and hence will breed true. If you mix the seeds of your dominants, you may go on for generations, groping blindly in the effort to fix a new race, without success. It is highly important to get these relations of dominant and recessive factors in Mendelian heredity clearly in mind. Indeed, the principle that mutually exclusive pairs of qualities are inde- pendently segregated and redistributed in the sec- ond generation of a hybrid progeny doubtless ex- ceeds in importance all other aspects of the problem of plant development. It was through independent discovery of this law of heredity that Mr. Burbank was enabled to make the major part of his conquests in the domain of practical plant breeding. DEALING WITH COMPLEX FACTOBS If you have grasped the essential principles of this Mendelian inheritance, your effort to com- bine the qualities of two different varieties of species of plant will represent a comparatively simple experiment so long as you have only one or two characters in mind. Suppose, by way of illustration, that you have in your garden a gladi- [158] THEORY AND PRACTICE olus with robust stalk that bears small flowers, and another variety with small stalk that bears large flowers. By crossing the two, and then in- breeding the cross-bred progeny, you may expect that in the second generation you will secure some plants that will bear large flowers on robust stalks, combining the good traits of the grandparents. But, as your experiments are extended, you will presently be confronted with instances in which the case is not so simple. You will be concerned not merely with the size of stalk and size of flower of your gladiolus, but with questions of color, of abundant bearing, and of keeping qualities as well. And you should know that with the inclusion of each new character the application of the Men- delian formula becomes increasingly complicated. The fundamental principle, as just outlined, is not altered, to be sure. Each pair of qualities (tall stalk versus short stalk, large flower versus small flower, red flower versus white flower, etc.) will be carried forward quite independently of all the other characters, and recessive traits will tend to reappear in one individual in four of the second- generation progeny. But, according to the simple law of chances, it comes about that where two pairs of Mendelian factors are in question the recessive factors, although appearing in one in- dividual in four of the progeny, will be combined in the same individual in only one case in sixteen. And when three pairs of hereditary factors are in question — for example, tall or short vines, pink or white flowers, and yellow or green pods, in [159] LUTHER BURBANK the case of Mendel's peas — the chance that the three successive qualities will be combined in the same individual of the second-generation progeny is only one in sixty-four. When four qualities are under consideration, the chance that they will be combined in any particular way is but one in two hundred and fifty-six. And with the inclusion of still other qualities, the geometrical ratio pro- gresses in such startling fashion as to give us as- surance that if we are attempting to combine ten different qualities in any given combination, the chance of doing so is about one in a million. Your first thought will be, perhaps, that you are not likely to consider more than two or three qualities as desirable in the case of any given plant. But a moment's reflection will show that here you are in error. Let us, for example, con- sider the perfected varieties of gladioli that have been developed in Mr. Burbank's experiment gardens. We shall find that there is scarcely a quality of bulb or stalk or flower that has not been modified in one direction or another. The bulb has been made to produce bulblets rapidly; they have been rendered hardy; and in particular they have been made relatively immune to disease. The stalks have been caused to grow to gigantic size, to stand firmly erect, and to bear flowers not merely on one side, as they were for- merly wont to do, but in spirals that show the flowers in a solid cluster, the blossoms facing in all directions. The flowers themselves have been very markedly increased in size, and given bril- [160] . THEORY AND PRACTICE liancy of coloration and remarkable keeping quali- ties. Some of them have been made to bear double rows of petals. Here, then, it appears that not fewer than ten separate and distinct qualities of the gladiolus plant have been under consideration in the course of Mr. Burbank 's experiments. It is obvious that the plant breeder could not be satisfied unless the good qualities were all combined in the same in- dividual plant. It would not at all suffice that one plant should have a hardy bulb while bearing poor flowers; or that another plant should have a splendid array of flowers on a frail stalk; or, again, that flowers of great beauty should have poor keeping quality. All the good qualities must be combined in the same individual. Suppose that Mr. Burbank started with one gladiolus plant having a splendid stalk, another having an immune bulb, a third with flowers of large size, a fourth with flowers of good keeping quality, etc. He could combine the plants two and two by cross-pollenizing ; and, by recombining again and again, in the fourth generation he would have blended the strains of all the ten original parents. But, as we have seen, the chance that any individual seedling of the next generation would combine the desirable traits of the ten orig- inal parent forms in just the right proportion is only one in a million. That is why Mr. Burbank raises his seedlings in such immense profusion. When the gladiolus experiments were under [161] LUTHER BURBANK way, for example, you might see in his greenhouse box after box, each showing tens of thousands of gladiolus seedlings. Day after day the scrutiny of these multitudes of little plants is continued, the obvious weaklings being weeded out, until a fraction of the original number remained to be transplanted to the fields, and permitted to de- velop and reveal their possibilities. But even after all the obvious undesirables were eliminated, there would still remain hundreds of thousands of plants to be set out in long rows in the experi- ment garden at Sebastopol, each given equal op- portunity with all the others. And, as we have seen, the ultimate result of the experiment would be the selection by Mr. Burbank at flowering time of perhaps a dozen or a score among all the hun- dreds of thousands as representing the closest approximation to the ideal type at which he aimed. Or perhaps a single plant would be found among the myriads that combined in fair measure all the good qualities that were sought. The experiment would then be completed by "line breeding " from this individual, saving all its seeds, and selecting among its progeny (which are sure to show a con- siderable range of variation) those that are best, until a race has been developed in which the de- sired qualities are accentuated to the maximum. STUDIES IN COLOB VAEIATION Probably you could not do better in beginning your experiments with the ornamental plants of [162] THEORY AND PRACTICE the dooryard than to work with reference to the modification of the color of the flowers. There are numerous familiar plants with any one of which you might work to advantage, — f or example, the gladiolus, the dahlia, the verbena, or the nasturtium. All of these plants show great color variation. In cross-breeding and selecting to secure new combinations of color, you are deal- ing with a restricted group of hereditary factors, and hence it will not be necessary to have large numbers of individual plants. Moreover, color in flowers is a new or recent development in the evo- lutionary sense, and hence modifications of color are more readily brought about than changes of root or stem or leaf. It is probable that all flowers were originally green, and that in the course of evolutionary de- velopment some flowers changed from green to blue and then to indigo and violet, while others ran the chromatic scale in the other direction, varying from green through yellow and orange to red. Eed and violet flowers are therefore prob- ably new in the evolutionary sense, blue and yellow flowers being old. White flowers may be due to having air in their cells, or to the blending of other colors — say yellow and blue. Yellow flowers may be due to the blending of red and green. In general, the mixture of factors for color in the heredity of a flower may rival in complexity the mixture of pigments on the canvas of an artist. The greatest interest of all, perhaps, for the amateur plant developer, attaches to the bringing [163] LUTHER BUKBANK out of unexpected colors that are submerged and hidden by more recently developed colors. As previously suggested, it is like the work of restor- ing an old masterpiece by removing the pigment of a modern painting overlying it. It is at least a plausible theory that new quali- ties tend to be dominant and old qualities re- cessive in the Mendelian sense, when brought in opposition through cross-breeding. Generally speaking, then, it may be expected that in cross- ing a red flower with a white one of the same species the progeny will be red. Violet crossed with white usually gives violet. Between yellow and blue there may not be much to choose in point of date of origin, and the result of a crossing may be doubtful. Any of the flowers mentioned may be worked with to advantage along these lines. An- interest- ing wild flower showing similar possibilities is the Indian paint brush or painted cup (Castilleia). Specimens of this growing in the same neighbor- hood may vary from scarlet, crimson, orange, yellow, and purple to pure white. Even the same individual may show flowers having most of these colors. Mr. Burbank suggests that the amateur might advantageously work with the painted cup in an effort to remove the overlying colors and reveal the pure blue; also to fix the different colors in different races. An interesting illustration of curious and unex- pected results that may be attained is furnished by one of Mr. Burbank 's hybrid pinks, in which [164] THEORY AND PRACTICE the individual flower varies in color, changing from one shade to another in the course of twenty- four hours. In the morning on first opening the flowers are pure white, by noon they are a bright pink, and toward evening they have changed to a deep crim- son. All the flowers at present under considera- tion furnish illustrations of dominance of one color factor over another, and on occasion of the blending of factors to produce new colors; but this case in which first one color and then another is dominant in the same flower is altogether out of the ordinary. ACCENTUATING DESIRED CHARACTERS It remains to be said that the distribution of the various qualities of the plant into opposing couples showing dominance and recessiveness is by no means so clean-cut and explicit in every case as the instances just cited might lead one to expect. In point of fact, it appears to be true that it is only the qualities that are of comparatively recent origin in the evolutionary sense that clearly Mendelize. Such qualities, for example, as the precise length of stem, color of flower, and color of seed pod are far less fundamental than the es- sential qualities of form and anatomical structure of stem and leaf, and the shape and arrangement of the petals and the essential organs of the flower. When these fundamentals are in ques- tion, the hybrid progeny usually show a blending [165] LUTHER BURBANK of the traits of the parents without clear dom- inance of one quality over another. But even where these qualities are blended in the first generation, there is likely to be a segre- gation and redistribution along Mendelian lines in the second generation, — giving rise to the phe- nomenon which breeders have been accustomed to speak of as reversion in one direction or the other toward the parental types. So you will do well to be on the lookout for the phenomena of Mendelian heredity in the second generation, even where you fail to find clear evidence of the dom- inance of a character in the first hybrid genera- tion. If, for example, you were to cross an orange poppy and a white one, as Mr. Burbank once did, securing only crimson-flowered progeny, you could carry the experiment forward another generation with full confidence that there would be interesting color revelations, enabling you perhaps to ana- lyze the component colors of the original parents in the second generation. In this particular case it is not unlikely that the original orange and white flowers contained blended pigments — per- haps red and yellow in one case, and yellow and blue in the other — and the breaking up and re- distribution of these hereditary factors through cross-breeding might prepare the way for the bringing out of hidden colors, leading ultimately, perhaps, to the production of a blue poppy. This illustration gives us a clew to yet another important aspect of our problem of plant breed- [166] THEORY AND PRACTICE ing. In the main discussion of Mendelian heredity above, we have spoken as if the thing contem- plated were the recombination of qualities that are already patent in one parent or the other of the original cross. But, in point of fact, the ob- ject sought by the plant breeder often goes far beyond the mere combination of existing quali- ties, as the case of the blue poppy at once sug- gests. The same thing is illustrated by a beautiful blue gladiolus which Mr. Burbank developed by cross- ing an imported gladiolus having a small purplish flower with a large white one of his own develop- ment. The mingling of hereditary factors here gave new combinations, and ultimately produced a large flower from which the obscuring pigments had been removed, so that an underlying blue, recessive to most other pigments, was revealed. It may be said that Mr. Burbank 's plant devel- opments have, as a rule, been similarly carried forward until qualities are so accentuated or modi- fied as to seem of a quite different order from the qualities of the parent forms. Here, for example, is a giant amaryllis with a flower almost a foot in diameter, the product of experiments in hy- bridizing and selection that involved no parent plant having a flower more than five or six inches in diameter. Here is another hybrid amaryllis bulb which puts forth a new bulblet every week, — fifty of them in a year, — although the parent forms from which this variety was developed were accustomed to produce only half a dozen new bulb- [167] LUTHER BURBANK lets in a season. Here is a hybrid between a crinum and an amaryllis, the bulb of which is far larger than a man's head, although neither parent had a bulb of unusual dimensions. And yonder is a hybrid gladiolus with a double row of petals, sprung from parents that bore flowers with no suggestion of doubleness. UNEARTHING EEMOTE HEREDITIES In attempting to explain these anomalies, we are led to conclude that every individual plant carries in its germ-plasm a multitude of heredi- tary factors that are, as it were, submerged be- neath other factors and prevented from making their presence tangibly manifest. There is appar- ently no limit to the number of generations through which a hereditary factor may be carried latent and seemingly impotent, yet always ready to manifest itself when the opportunity arises. And the opportunity may come through a hybrid- ization that brings new coteries of hereditary fac- tors into the combination, with resultant redis- tributions that no one could predict, but which may be very striking and highly suggestive and interesting in their manifestations. The gigantic trumpet of the hybrid amaryllis and the enormous bulb of the hybrid crinum are reminiscent of past ages when remote ancestors of these plants grew under favoring tropical con- ditions of an earlier geographical era, and put forth flowers and bulbs of which the best present- [168] BURBANK ONIONS GROWN FOR SEED. Mr. Burbank has worked extensively with the onion, as with numerous other members of the tribe of alliums. Here we see a field of perfected Burbank onions that have distinctly ornamental flowers. The excellent character of the bulbs may be inferred from the size and vigorous development of the tops. THEORY AND PRACTICE day specimens are but dwarfed and insignificant replicas. Similarly the double flowers that form so at- tractive a feature in our gardens — roses, dahlias, marigolds, and the rest — are probably reminis- cent of clustered flowers of the antique world. What is now the composite head of a single dahlia or marigold or daisy was probably, in its pri- mordial state, a cluster of flowers. Through nat- ural selection such a cluster made an experiment in communism, in which finally hundreds of flow- ers were grouped, with a single circle of florets to advertise their location to the insects. This represented great economy, and the plan became enormously popular, so that the composites are among the most abundant of flowers. But each individual blossom in a composite flower head car- ries in its germ-plasm the factors for the develop- ment of an independent corolla, and under favor- ing conditions — through hybridization or through changed environment — this potentiality is realized in the production of what we term a double flower. In this way only can we explain such a phe- nomenon as the rapid production of races of double dahlias in the relatively short period since the single dahlia was brought from Mexico and given a place in the cultivated flower garden. [169] CHAPTER IX BURBANK'S METHOD OF BEAUTIFYING LAWN AND DOORYARD THIS chapter tells how to apply Mr. Bur- bank's method to the care and beautifica- tion of the lawn and dooryard in their en- tirety. It deals not alone with the lawn itself, but with the bed flowers and ornamental vines that beautify the dooryard. Mr. Burbank has pro- duced wonderful new flowering vines and numer- ous ornamental shrubs of great beauty. His work with the canna, gladiolus, watsonia, amaryllis, and rose has been as remarkable as almost any other work that he has done. Many visitors to Mr. Burbank 's home in Santa Rosa in recent years have been much interested in the lawn about his dwelling. At a little distance this looked much like any other lawn that is well covered with grass. But closer inspection showed that the velvety cover- ing was not made by grass, but by a trailing vine. It was in reality a species of verbena of a peculiar type. It is known to the botanist as Lippia, and this word serves as well as any other for a popular name. Lippias of several species were sent to Mr. Bur- bank from Chile, and he has cultivated and devel- [170] LAWN AND DOCKYARD oped two or three varieties with especial refer- ence to their utility as substitutes for lawn grass. When Mr. Burbank first procured the seed of the wild species he observed a good deal of variation among the seedlings, and in the second season he raised about ten thousand plants, each one of which was given a little space in order that its individual peculiarities as to rapidity of growth, tendency to spread, and color of foliage might be tested. From among these ten thousand plants about half a dozen were saved, and the descendants of these constitute several varieties of lippias that have striking peculiarities. One of these will spread on an ordinary soil over a circle about ten feet in diameter. This form, Mr. Burbank points out, would be very valuable for growing in sunny places, and in particular along irrigat- ing ditches or river banks where the soil is sub- ject to wash. Other varieties grow less rapidly, but have small leaves that lie very close to the ground, making a most beautiful and satisfactory velvety lawn. There is a marked difference in color in the different varieties, so that charming contrasts may be produced by planting different portions of the lawn with different varieties. In addition to their rapid and compact growth, Mr. Burbank 's perfected lippias are adapted to dry soil, requiring not one-tenth the water that blue-grass or other ordinary lawn grass requires, and keeping in good condition with a fraction of [171] LUTHER BURBANK the care that must be bestowed on lawns of blue- grass or clover. Curiously enough the lippia lawn makes the best appearance where it is frequently trod upon and subjected to rough treatment. All in all, then, the developed lippia constitutes a remarkable lawn cover, and one that must in- crease in popularity in all climates to which it is adapted. Unfortunately the plant is rather tender, and is likely to winter-kill in the northern parts of the United States. But it is expected that hardy varieties will be developed by further experiments in selective breeding, and the lippia will then become a formidable rival of the blue- grass for lawns everywhere, and in particular in regions where there are long periods of summer drought. OTHER SUBSTITUTES FOE GEASS Very recently Mr. Burbank has experimented successfully with several other substitutes for grass. He has found two plants that are superior to the lippias for growth in soil subject to washing ; for example, along creeks, or irrigating ditches, or on hillsides. One of these plants is a species of Mesembryanthemum, which grows along most seacoasts. This produces an enormous amount of dense foliage, which is not moved even by a very heavy stream of water. The other plant is a selected variety of the [172] LAWN AND DOCKYARD trailing myrtle (Vinca minor). This forms a great mass of long white roots, and long vines with abundant evergreen foliage, which resist stream wash by shingling the whole surface so that the water can scarcely reach the soil. Sev- eral other plants are under observation with refer- ence to their possible utility as substitutes for blue-grass on ordinary lawns; in particular the attempt being made to develop varieties that are hardier than the lippias. Among the most interesting of experiments thus far conducted are those having to do with the trailing species of hypericum from the moun- tains of eastern Chile. On the lawn in front of Mr. Burbank's dwelling at the present moment this plant has taken the place of the lippias. It makes a close mat of green, and it does not turn brown in winter. It grows somewhat less rapidly than the lippia, but there is good promise that selected varieties will make an excellent lawn cover. Somewhat similar species of hypericum have recently been introduced by Mr. Burbank from Russia and from other parts of central and northern Europe. These show the same creeping habit, and no doubt will be hardy everywhere. Even the first generation from the wild native plants, these hypericums show a wonderful varia- tion as to rapidity and compactness of growth. There is every reason to expect, then, that a few years of selective breeding, under Mr. Burbank's skillful supervision, will supply a lawn plant for [173] LUTHER BURBANK all climates in many ways superior to anything hitherto known. Mr. Burbank makes this predic- tion with some confidence ; adding, however, that the new plant may be a little more difficult to establish than ordinary lawn grass. All the hypericums will stand a great amount of drought and ill treatment. Tramping does not injure them, and they may be moved like ordinary lawn grass. Observation of the varieties already under cultivation at Santa Rosa gives assurance that here is material from which a valuable new type of lawn cover will be developed. There is no reason why the amateur should not make experiments in selective breeding with the hy- pericums, even in localities where the more tender lippia cannot be grown. OKDINAKY LAWNS AND THEIR CAEE Until the lippias have been rendered hardy, however, or the hypericum or the other plants more fully developed, most residents of the north- ern climates must be content with the lawn grasses of the old familiar type, with the blue-grass at the head of the list. Seeds for these grasses vary a good deal in quality, and Mr. Burbank urges that they shall be secured only of a reputable dealer. Pure blue- grass he thinks better for the ordinary lawn than any mixture. The grasses themselves offer opportunity for great improvement through hybridizing and se- [174] LAWN AND DOORYARD lective breeding, but the hybridizing of plants that have such small and inconspicuous flowers requires a good deal of skill. To such as wish to undertake it, however, it may be said that the process of cross-fertilization is in no wise differ- ent in principle from that employed in the case of other flowers. It will be necessary in many cases to work with a magnifying-glass, and deli- cacy of manipulation is essential. But if you have acquired skill through practice on the larger flowers of orchard and garden, the fertilizing of the grasses will offer no insuperable difficulties. In particular, you may find interest in experi- menting with some of the large ornamental grasses, such as pampas grass, which may readily be hybridized, and greatly developed as to size and artistic quality of the plume-like flower heads. Some of the pampas grasses bear the staminate and pistillate flowers in separate panicles, and hence may be cross-fertilized by merely dusting one flower cluster against another. At the time when the pampas grasses were more in vogue than they now are, Mr. Burbank developed many inter- esting varieties, using precisely the same methods of hybridization and selection that have been de- tailed in connection with the development of other plants. Other grasses with which anyone may work, and which give promise of results of vast economic importance, are the familiar cereals, wheat, oats, and rye. Here fertilization is difficult, as the flowers are borne in closed receptacles; but, on [175] LUTHER BURBANK the other hand, there is little danger of vitia- tion of the experiments through accidental cross- ing. As an instance of what may be done, it may be noted that Professor Biffin, at Cambridge Uni- versity, England, recently succeeded in develop- ing a variety of wheat that promises to revolu- tionize the wheat-growing industry in England, by combining the strains of a hardy wheat of poor quality with a weak-stalked wheat having a good head. The experiment was carried out along Mendelian lines, and perfected in three gen- erations, giving the farmers of England a wheat of good quality, immune to the rust that had devastated their fields. Mr. Burbank has under way a series of experi- ments in which he has crossed all available va- rieties of wheat. In his experiment garden the present season one row of these hybrid wheats was found to have vitality that enabled it to stand up under drought and wind when all the com- panion rows (representing different combina- tions) had wilted. It is easily within the range of the experiments of any amateur to conduct similar tests in cross- breeding and selection, starting with standard varieties of wheat or oats or rye, and working with an eye to the development of hardy and un- usually productive varieties. It has been pointed out that anyone who would develop a race of wheat that would bear on the average one kernel more to the head would thereby add millions of [176] MR. BURBANK PLANTING CHOICE SEEDS The seeds are being planted in a box or " flat " of the usual type. The work is being done in the room to the conservatory. Note the pile of prepared earth in the background, and the pots for transplanting seedlings that are to be given special attention. LAWN AND DOCKYARD bushels to the annual product, and thus confer a magnificent benefaction on the race. Bear in mind that the experiments necessary for the development of new varieties of cereals may be made in a plot of ground a few feet square. There is no better use to which you could put one or two of the plots set aside on your lawn for ornamental plants. The cereal grasses are grace- ful plants, which, properly placed, would consti- tute a pleasing and novel feature of lawn decora- tion. And experiments with them might result in developments vastly surpassing in importance all other possibilities of your flower or vegetable garden. It may fairly be assumed, however, that you are interested rather in the preparation of the soil for the lawn and in its care than in the im- provement of the lawn grasses proper, inasmuch as these have already reached an advanced stage of development at the hands of numberless pro- fessional gardeners. And as to this aspect of the matter, Mr. Bur- bank cites an experience of his own that is il- luminative, and may well be narrated. It appears that when he first purchased the four-acre plot of ground at Santa Rosa that was afterwards to be- come so famous as the seat of his experimental labors, this land was wet and soggy of soil, and entirely unproductive. It had been the bottom of a pond at some remote period, and the soil re- tained an excess of moisture. Mr. Burbank's first move after purchasing the place was to drain it [177] LUTHER BURBANK properly. This was accomplished by running a main line of four-inch tiles down the center of the tract with laterals of two-inch tiles joining it at right angles at intervals of forty feet. The lat- erals gather surplus water quickly after heavy rain, and the main pipe carries it to a small stream nearby. The slope of the pipes is one foot in forty feet. THE WOKLD'S MOST PKODUCTIVE ACEES At first thought it seems rather surprising that two-inch pipes forty feet apart will adequately drain a moist soil. But Mr. Burbank points out that the drainage pipes are working day and night, with no rest on Sundays, and that they carry a great amount of water in the course of twenty- four hours. In point of fact, this system of two- inch laterals with a four-inch central pipe proved eminently satisfactory at Santa Rosa from the outset, and no change has been necessary in the thirty years it has been in operation. The pipes require no attention whatever, — they have never been even inspected since they were put down. It is of course highly essential that each piece of tiling as originally laid should be perfect, and that the entire system should be carefully ad- justed at the proper grade. The joints should be packed with clay. If any part of the line sags, sediment will collect and retard the flow of water. By the mere installation of this simple system [178] LAWN AND DOCKYARD of pipes, the heavy adobe soil of Mr. Burbank's Santa Eosa place was made arable. The soil was then enriched by plowing in eighteen hundred loads of manure. Localized beds were subse- quently modified to meet the needs of bulbous plants by mixing sand with the soil. The net result of this treatment was to trans- form a tract that would scarcely support vegeta- tion of any kind into the most productive four acres perhaps to be found anywhere in the tem- perate zone. Doubtless there is no other tract of similar size anywhere in the world that has pro- duced so varied a crop of vegetation and such pro- fusion of new and interesting and beautiful forms of plant life year after year as these transformed acres at Santa Rosa. Mr. Burbank's experience affords a lesson by which everyone who has a small tract of land that he wishes to put in condition for lawn or garden may profit. Even if your land lies in a region where there is drought in summer, there are periods of the year when the ground is unduly saturated with water, and when it must be drained to permit the proper aeration of the roots of the plants. The drainage pipes will not take water from the soil except when there is an excess of it. For dry soil absorbs water sponge-like through capillarity. So, unless your land is located on a hillside where there is the best possible opportunity for natural drainage, you will do well to install a system of drainage tiles like that described, and [179] LUTHER BURBANK you may confidently expect that your lawn and garden will be noticeably benefited thereby. As to the preparation of the soil itself, every- thing depends upon the local conditions, and only general rules can be given. If the soil is very sandy, it will be benefited by having clayey loam spread over it and incorporated with it by plow- ing. And there are very few soils that are so rich that they will not be benefited by thorough fertilizing. For this purpose barnyard manure has exceptional value, not only because it sup- plies plant foods, but also because it gives the right texture to the soil. Leaf mold from the woods, if it can be secured, has value for the same reason. Nowadays it is well understood that the physical texture of the soil is almost as important as its chemical composition. The roots of the plants require air as well as water, and they will not thrive in a soil that lacks porosity. In the garden the soil is kept porous by constant cultivation, but this is obviously not possible with the lawn ; hence it is especially important that soil for the lawn shall have the right texture before the grass seed is sown. SUPPLYING WATER The lawn that needs to be protected against an excess of water at one season by a system of drainage may at another season require artificial watering even more imperatively. The question [180] LAWN AND DOCKYARD of artificial irrigation is therefore no less impor- tant than that of artificial drainage. Here again the needs of the lawn call for special consideration, both because the soil cannot be kept porous by cultivation and because the roots of the grass permeate the entire surface and exhaust the water supply very rapidly. The fault with most of the common sprinklers used to irrigate lawns and small gardens, says Mr. Burbank, is that they do not distribute the water evenly. Most of them cover a circular space, and there is always some part of the soil which has too much water while other parts have too little. One of the most important points in irrigation is to have the water distributed evenly. Some of the flat or fishtail sprinklers distribute the water better than the older forms, but Mr. Burbank especially commends the newer system of overhead irrigation as far superior to the old forms of sprinkling. He recommends the use of a number of one-inch galvanized pipes with noz- zles placed along the sides from twelve to twenty inches apart. The pipes, mounted on stakes at a convenient height, are connected with the water supply by ordinary rubber hose. A single system of pipes will water a space evenly to a distance of from twenty-five to fifty feet on either side. Thus an ordinary lawn may be supplied from a line of pipes at either side, and these pipes may be con- cealed by a trellis of ornamental vines. The system may be so modified that the pipes instead of being held on permanent stakes are car- [181] LUTHER BURBANK ried from one place to another and placed on tem- porary stakes or movable stands. A modification of the system is to have the pipes underground, just at the surface. This has the advantage of having the pipes out of sight, but the system is more costly to install. The fact that the iron pipes last for many years should be taken into account, however. The part of the ordinary sprinkling system that deteriorates most rapidly is the rubber hose. The permanency of the iron pipe system soon compensates for the initial cost. Moreover, the saving in both time and water is notable, and the lawn is given a much more evenly distributed supply of moisture. The same system may advantageously be util- ized in the flower garden and vegetable garden. A single line of pipe may be arranged so that it will water the beds on either side. Where the prevailing winds come from one direction through- out the summer, it is advantageous to place the irrigating pipe on the windward side of the lawn or garden to gain the aid of the wind in spraying the water over a wider surface. OENAMENTAL FLOWEE BEDS There are few other lines of plant experiment to which Mr. Burbank has given greater attention than that having to do with the production of ornamental flowers adapted for massed display in beds on the lawn or in the dooryard. He has introduced, for example, half a dozen [182] LAWN AND DOCKYARD new forms of callas, including varieties with spotted leaves that have a peculiarly striking massed effect; a dozen new dahlias of the most varied and beautiful forms and colors (among others, the first fully double ones, and a fragrant variety) ; more than twenty new gladioli of rare beauty; a large number of poppies of the most exquisite quality of petal and of rare colors ; and numerous roses that reveal an unmistakable Bur- bank quality. Then, too, there are cannas, ver- benas, larkspurs, myrtles, codetias, lobelias, pentstemons, eriophyllums, firecracker flowers, primroses, and the wonderful giant amaryllis, with a coterie of exotic forms of less familiar name, on the one hand, and perfected varieties of such familiar flowers as the milkweed and iris and petunia and bleeding-heart and goldenrod, on the other. All of these have been brought under Mr. Bur- bank's tutorage, and have been made to reveal new possibilities of development of form or color or fragrance or profuseness of bearing. The ex- periment gardens at Santa Rosa and Sebastopol are objects of admiring attention to hundreds of visitors throughout the season, and the new forms of flowers here developed are sent out to gladden the hearts of flower lovers everywhere in the world. However varied the qualities of the different flowers, the same general principles of develop- ment apply to all of them. Hybridization and se- lection are the keys to progress and plant develop- [183] LUTHER BURBANK ment, whether we deal with gladiolus or with canna, with dahlia or with petunia, with mallow or with amaryllis. There are important details of difference, however, some of which will be out- lined in a moment. There is no reason why you should not improve upon any one of the flowers that ornament your lawn or dooryard. By applying your own taste in the selection of plants whose seeds shall be preserved, you may put the imprint of your own personality on new varieties, just as Mr. Burbank has put the imprint of his personality on the varieties that are now sent out from Santa Rosa. Perhaps it may not have occurred to you, but it is nevertheless true, that the Burbank flowers have delicacy and artistic quality of form, and harmonious blending of color, and exquisite per- fume because Mr. Burbank himself is a man of refined sensibilities to whom these qualities ap- peal. By the same token, you may develop, if you so elect, in the course of two or three seasons, new varieties of flowers that will represent your personality quite as fully as you are represented by your costume or the equipment of your bou- doir. To have a flower garden of such unique individuality is surely a worthy ambition ; and it is one that may readily be gratified. IMPKOVING THE GLADIOLUS As illustrating the possibility of doing remark- able work with a very common plant, it is worth [184] A BURBANK HYBRID TIGRIDIA. This is one of many interesting varieties of Hybrid Tigridia that Mr. Burbank has developed. The plants are spotted and not striped, yet there does seem to be something tiger-like about this richly caparisoned and oriental-seeming specimen. It is rather curious to reflect that the spots on the flower are intended to make it con- spicuous, whereas the striped coat of its namesake is calculated to make the animal invisible in the jungle. LAWN AND DOCKYARD while to recall details already given as to Mr. Burbank rs work with the gladiolus. He has worked with many varieties, and has raised the bulbs by hundreds of thousands; and there is scarcely a quality of bulb or stalk or flower that he has not modified in one direction or another. The bulbs have been made to produce bulblets rapidly; they have been rendered hardy; and in particular they have been made relatively immune to disease. The stalks have been caused to grow to gigantic size, and to bear flowers not merely on one side, as they were formerly wont to do, but in spirals that showed the flowers in a solid cluster, the blossoms facing in all directions. The flowers themselves have been very markedly increased in size, and given brilliancy of coloration and re- markable keeping quality. Mr. Burbank says that the possibilities in ex- perimenting with color in the gladiolus rival the experiments that a painter makes with the pig- ments of his palette. Mr. Burbank himself has a remarkable color sense, and he takes particular delight in modifying the shades of color of his flower creations, and enhancing their delicacy and beauty. He has found that certain combinations of colors can be made, quite as in the case of the artist's pigments, with pleasing results, and that other combinations should be avoided. If a pink gladiolus, for example, is combined with a white one, the result will probably be a paler pink that is not pleasing. On the other hand, it was by combining a small purplish gladiolus, imported [185] LUTHER BURBANK from Europe, with a white one that Mr. Burbank produced his remarkable blue gladiolus. Flower lovers are aware that the gladiolus, like the poppy and rose, is not partial to the color blue. Yet Mr. Burbank has succeeded, after a long term of experimentation, in developing a blue strain of gladiolus that is as beautiful as it is unusual. Mention has been made of the white gladiolus, but it should be explained that this flower is not pure white, as comparison with a white watsonia flower will show. The white of the watsonia has been termed "the whitest white in nature." It is of interest to recall that the progenitor of the white watsonia was a "sport" found in the native home of the plant, South Africa, in a region where watsonias of the normal reddish color were abundant. The white sport bred true, and it was presently introduced in the gardens of Europe and America. Unfortunately, the watsonia is a rather tender plant, and this has interfered with its popularity in the eastern United States. Yet it is a plant worthy of cultivation, and one that in many ways rivals the gladiolus, which it somewhat resembles. It has been a favorite flower with Mr. Burbank, who, besides improving it in many features of bulb and stalk, has devoted particular attention to the development of its color possibilities. By combining the white and red strains, and making various recombinations of the offspring through many generations, and by rigid selection among the flowers showing slight variation, he has devel- [186] LAWN AND DOCKYARD oped watsonias of multiform colors, some of which show delicate shades of purple and pink that are rivaled only by the orchids. THE EOTATION OF CHOPS In his work with the bulbous plants, Mr. Bur- bank has met with peculiar difficulties because from time to time his fields have been invaded by a pestiferous little mammal, the pocket gopher, which burrows underground, and which has on occasion destroyed thousands of his choicest bulbs before the presence of the marauder was detected. 'At one time the gophers became so destructive — seeming always, as Mr. Burbank says, to select his choicest bulbs — that the plant breeder was led to give up the cultivation of the gladiolus and of various allied bulbous plants. Only after almost numberless experiments did he find a method of coping with the rodents. The successful device was a kind of gun that is exploded just at the moment when the body of the gopher is in contact with a quantity of powder. After this device was in hand, Mr. Burbank re- turned to the interrupted line of experiments with the bulbs, and his experiments with plants of this character have been among his most important works of recent years. In carrying out these experiments on an ex- tensive scale, he has discovered that there are other pests that are almost as destructive as the gopher. The bulbous plants, indeed, are pecul- [187] LUTHER BURBANK iarly subject to the attacks of various fungous and insect foes. It is in the endeavor to ward off these foes that most bulbs have developed a bitter principle. In many cases, however, the in- sects refuse to be discouraged by the bitter taste, and eat the bulbs with avidity, often working de- struction to the choicest specimens, and making progress impossible. To guard against such mishaps, Mr. Burbank recommends that any soil in which bulbous plants are grown should, if possible, be thoroughly sterilized before the bulbs are set out. Where the quantity is small, it may be possible to dig up the soil and sterilize it by baking. When this is im- possible, something may be accomplished by the use of germicides. In recent years Mr. Burbank has used large quantities of a liquid preparation known as tuolene, and he regards this as the best germicide that he has ever used. By impregnating the soil with this solution, protection is given the delicate bulbous plants, and they may thrive where, if not given such aid, they would inevitably have perished. It is impossible, however, to rid the soil per- manently of all fungous and insect intruders. Where bulbs are grown in the same soil, in suc- cessive seasons, these enemies are sure to accumu- late. Moreover, the roots of plants may give out excretions that render the soil noxious for that particular species. Therefore, Mr. Burbank es- pecially recommends that anyone having to do with bulbous plants should change the location [188] LAWN AND DOCKYARD year by year, never having the same bulbs in a bed two years in succession. It is better, indeed, not to raise plants of any one kind for successive seasons in a bed, but to alternate between bulbous plants and annuals grown from the seed. Failure to carry out such a rotation of crops is a very common source of failure with the amateur gar- dener. It is not at all unusual to see an amateur obtain excellent results for one or two seasons, and then to have her garden degenerate simply because she has attempted to raise the same kind of plant year after year in the same location. By transposing the different plants — putting the gladioli this year where petunias, for example, were grown last year, and the like — all the plants may be kept in vigorous growth. Attention to this detail may make all the difference between suc- cess and failure in the disposition of flower beds to ornament the dooryard. If it is your desire to keep bulbous plants year after year in the same bed, you may accomplish this if you are willing to take the trouble to dig out the top soil and pile it up in some out-of-the- way corner and replace it with other soil, which will in turn be dug up and piled for renovation next season. After lying in a heap exposed to air and sun for a season, the dirt becomes thor- oughly sterilized, and may be restored for use the ensuing year. In other words, you may have two coats of soil for your flower bed, to use in alternate seasons. [189] LUTHER BURBANK Mr. Burbank does not employ this method, as he works on too comprehensive a scale, but it is used by Professor Hugo De Vries, the celebrated Amsterdam botanist. In his experiment gardens at Amsterdam, you may see heaps of dirt being thus renovated with the aid of time and the ele- ments, and any amateur who operates on a small scale may imitate the example. Ordinarily, of course, it will be more expedient to practice rotation of crops, giving your soil the additional benefit of occasional sprinkling with a germicide. But for the benefit of the small beds located in some particular part of the lawn where you wish, for example, to keep cannas or gladioli or tulips season after season, the more trouble- some but highly effective method of using two coatings of soil in alternate years may be worthy of consideration. SOME GIGANTIC FLOWEBS Among Mr. Burbank 's almost endless experi- ments with bulbous plants, perhaps none have greater interest than those that have to do with the not very familiar plants which are known to the horticulturist under the name of Amaryllis, but which really belong to several somewhat closely allied genera. One true amaryllis (the so-called belladonna lily) is a rather common plant indigenous to the United States. But the plants that go by the name in horticultural circles are mostly of the genus Hippeastrum, and have [190] LAWN AND DOCKYARD been brought to us from the tropics. There are also the allied genera of Crinum and Sprekelia. Mr. Burbank has hybridized these plants in a great number of combinations, and has produced some very striking and remarkable results. His work with the plants of the genus Eip- peastrum — making up the body of the flowers usu- ally termed amaryllis — has had to do with a num- ber of species that have been long under cultiva- tion, including some that have been earlier hy- bridized, as well as with less familiar species im- ported from tropical regions. At first Mr. Burbank had difficulty in hybrid- izing these plants, but he presently discovered that the difficulty lay solely in the selection of just the right time to apply the pollen. The pistil does not become mature until after the pollen of the same flower has been discharged. By bearing this in mind, and gathering pollen on a watch crystal, if necessary, to await the maturing of the pistil of another flower, cross-fertilization presents no dif- ficulties. By working for twelve or fifteen suc- cessive seasons, Mr. Burbank produced complex hybrids that are really very remarkable plants. Some of them have enormous bulbs, with a pro- pensity to produce bulblets at a really astonish- ing rate. Many varieties of amaryllis produce only one or two bulbs in a season, which accounts for the fact that these bulbs are costly. But Mr. Burbank so stimulated the bulb-producing capacity of his hybrid varieties that his most prolific species will [191] LUTHER BURBANK produce a new bulb every week, or fifty new bulbs in a year. In point of prolific bearing, there was cor- responding progress. Not only do the hybrid spe- cies produce large stalks, but they produce four or five stalks to a bulb, instead of the original two or three, and sometimes as many as twelve flowers to the stem (when they have remained in the ground for a few seasons), instead of the original four or five flowers in a cluster. The en- hanced fecundity of the new forms is supple- mented by their tendency to early bearing. They will sometimes bloom the second year from seed, and on the average they bloom in three or four years; whereas the old forms sometimes required six or eight years to come to maturity. Thus Mr. Burbank has pretty nearly cut in half the time from seed to blossom in the amaryllis. Hy- bridization and selective breeding are of course the magic methods that accomplish these results. But the most spectacular transformation has to do with the flowers themselves. In the original species, the largest flower seldom attained a diam- eter of more than five or six inches. Mr. Bur- bank's hybrid species of giant amaryllis produce flowers that are almost a foot in diameter. These megaphone-like flowers of the giant amaryllis are among the most striking, as well as among the most beautiful, objects to be seen in Mr. Burbank 's experiment gardens. It should be added that the giant amaryllis does not produce its largest flowers until it has at- [192] LAWN AND DOORYARD tained full maturity. The flowers may increase in size for several successive seasons as the bulb gains size and strength. Moreover, it is necessary to give the bulbs good treatment — rich soil, plenty of water and sunlight — in order to have them reveal their full possi- bilities. In particular, Mr. Burbank points out that a bulb that has been ill-treated in its first season will never produce a large flower, even though it have the hereditary factors for large blooming. The amount of patient work required to secure just the right combinations will be appreciated when it is said that Mr. Burbank experimented for about fourteen years before obtaining varie- ties of amaryllis that seemed worthy of intro- duction. I had an illustration of the precocity of some of these plants when an amaryllis bulb brought from Santa Rosa and potted indoors in New York in the month of April sent up a flower stalk and put forth the first of a series of beautiful blos- soms in the extraordinary short space of eight days. ENORMOUS BULBS OF HYBEID CRINUM AND AMAEYLLIS Mr. Burbank has crossed the true amaryllis with plants of the genus Crinum with spectacular results. Some of the hybrids have enormous bulbs, — [193] LUTHER BURBANK far larger than a man's head, — and their flowers seem intermediate in character between those of the parents. But the two plants are evidently pretty nearly at the limits of affinity, and while the hybrids put forth flowers abundantly, they do not have viable seeds. Of course the new plants may be propagated indefinitely from bulbs, so that the hybrid crinums constitute interesting permanent varieties. But the experiment cannot be carried beyond the first generation because the hybrids are sterile. Such, at least, has been Mr. Burbank's experience. It is quite possible, however, that it may be feasible to find species of crinums or individual flowers that would produce fertile offspring when crossed with the amaryllis. At least further experimentation along this line is worth making. It would also be of interest to attempt to cross the crinums with the hippeastrum or tropical amaryllis, a combination that Mr. Burbank has attempted many times, but hitherto without success. All in all, the plants of the amaryllis tribe fur- nish rare opportunities for experiment in the hands of the amateur, particularly since Mr. Bur- bank has developed species that are sufficiently hardy to thrive out of doors in our northern lati- tudes. A good deal of patience is required, to be sure, in awaiting the maturation of the flowers ; but experiments in cross-pollenation may be begun without delay, if you start with mature bulbs. The pollenizing of the flowers presents no difficul- [194] LAWN AND DOCKYARD ties whatever, if care is taken to apply the pollen to the pistil when it is fully mature. To make sure of this it is well to apply the pollen on several successive days. With some spe- cies the maturing of the pistil is marked by its curving upward; in others it elongates rapidly, the result in either case being to place the pistil where it will be likely to receive pollen from the large moths or the humming-birds that ordinarily fertilize tubular blossoms of this type. WORKING WITH THE RESPONSIVE DAHLIA Apropos of the pollenizing, it may be well to call attention to difficulties that confront the worker when he deals with the composite flowers, of which the various sunflowers and the dahlia furnish familiar examples. The peculiarity of the composite flower, it will be recalled, is that a large number of blossoms are gathered in a single head, about which a conspicuous circle of ray flowers or florets is displayed. This is an example of communism in the plant world, as a single circle of petal-like appendages is made to serve as an advertisement to insects for all the numerous blossoms of the cluster, whereas ordinary flowers have a set of petals for each individual blossom. But whereas this ar- rangement is eminently satisfactory from the standpoint of the plant itself, the grouping of flowers in a mass obviously complicates the prob- lem of the hand pollenizer. [195] LUTHER BURBANK The best practical method in eross-pollenizing composite flowers — for example, dahlias — is to wash away with a spray of water the pollen of the flower head that is to be fertilized, afterwards rubbing its surface gently with the pollenizing head plucked from another plant. Of course you cannot always be sure that the flowers have not been fertilized by pollen from other florets in the same head before you began operations. More- over, as the flowers of the head do not mature all at the same time, but gradually ripen from cir- cumference to center, you must repeat the opera- tion on several successive days to make sure of hybridizing a large proportion of the blossoms in a given head. At best there will be an element of uncertainty about the result, but this will give additional zest to the experiment and increase the interest with which you will await the blossoming next season of the plants grown from the seeds of a flower head thus manipulated. The dahlia furnishes perhaps the best example of a familiar composite flower with which you may begin your experiments in this somewhat more difficult type of cross-pollenizing. As these flow- ers are at their best late in the fall, there is still abundant opportunity for work during the present season. And notwithstanding the large amount of work that has been done with the dahlia, you may hope to secure very interesting new devel- opments. Mr. Burbank has worked very extensively with [196] LAWN AND DOCKYARD this group of flowers, and has produced some very striking hybrids by combining the familiar garden species with wild species brought from Mexico. You may secure a sufficient variety of dahlias from any florist to give ample opportunity for further hybridizing experiments. No dooryafd would be complete in its autumnal floral display that did not have a bed or two of these very at- tractive flowers. The wild progenitors of the modern races of dahlias have flowers with a single row of florets, like the wild sunflowers. The complex rounded heads of many cultivated varieties are due to the transformation of the minute and originally incon- spicuous florets of the cluster under the stimula- tive influences of changed environment and arti- ficial cultivation. To observe the contrast between the wild dah- lia and its cultivated descendant is to receive a vivid object lesson in the possibilities of flower development. Even without hybridizing, you may develop a great variety of dahlias. All the varieties under cultivation are complex in their heritage, and the fact that the plants may be multiplied by division has made it unnecessary to carry selective breed- ing to the stage of fixing qualities so that plants grown from the seed will reproduce in detail the features of their parent plants. You may find endless amusement and interest in selecting new varieties from among the plants grown from a single packet of seeds, and you may [197] LUTHER BURBANK try your hand at fixing new types by careful in- breeding and further selection. A very interest- ing experiment may be made by planting all the seeds from a single dahlia head in separate plots ; carefully screening each plant against cross- pollenation, and noting results in the second filial generation. Each seed may seem to give a unique variety, and by persistent selection through sev- eral generations, following the same method, you may secure an endless variety of interesting types. Meantime, any individual that you prize may serve as the progenitor, through root division, of an entire race exactly like itself. STUDIES IN COLOR VARIATION" The dahlia also offers large possibilities for the study of color variation, and for experiment in the blending of different colors to produce new types. As illustrating the possibilities of develop- ment of this flower, it may be recalled that this is one of the most recent acquisitions in the flower garden, the dahlia having been brought under cul- tivation only four or five human generations ago. The species of dahlia first introduced from Mexico was brought to England in the year 1789 by the Marchioness of Butte. It had the general form of a very large daisy, and it resembled numerous familiar wild sunflower-like composites, except that its floral envelope was dull scarlet with a yellow center. Subsequently other species were introduced, and through hybridization and selec- [198] LAWN AND DOCKYARD tion the flower was not only made to take on the greatly modified form with which we are familiar, but its color scheme was indefinitely modified, al- though the original red and yellow, together with the white and crimson of certain other species, form the basis of coloration of all the cultivated varieties. Almost any of these show sufficient diversity of color to make interesting experiments in blending and modifying their color scheme feasible. Equally interesting studies of color variation may be made with the different types of roses. Added zest is given to these experiments by the fact that many of the roses are not readily cross- fertilized. Mr. Burbank tells us, for example, that he has grown upward of two hundred thousand seedlings from the crimson rambler pollenated with all the ordinary roses that are under culti- vation in California. He found that the pollen of only a few roses proved effective. Here and there a rose like the Empress of India or the Cecil Bruner would pollenize readily with the rambler, and the hybrid progeny would sometimes cross readily with numerous other hybridized roses with which the crimson rambler itself could be united with difficulty, or not at all. Under these conditions, it is obvious that the hybrids soon become very complex as to their ancestry, and the sorting out and isolation of their heredi- tary factors in new combinations may become a fascinating puzzle. Still another familiar flower with which work [199] LUTHER BUKBANK in color variation may readily be carried out is the verbena.' ' The ancestors of the cultivated ver- bena were South American plants, and it is be- lieved that there are four chief species that have been variously hybridized to produce all the forms now under cultivation. One of the original species bears flowers of brilliant red, two others have flowers that are rosy or purple in color, and the flowers of the fourth are pure white.77 The hybridized races show the breaking up of these colors, quite as might be expected, with a presentation of all the primary colors in many of their hues and gradations, although pure blues are not well represented, and pure yellow is very ex- ceptional. To experiment in the production of new colors and combination of colors, it is not necessary to hybridize the verbenas, as few if any of the familiar forms breed true from the seed. (( You may secure all the variation that is desirable among the plants grown from a single packet of seeds, and may isolate and fix by selection an in- definite number of new types with color schemes that please your eye. It is possible, also, that you may find among your verbenas an exceptional flower with a pleasing odor, and this also may serve as the basis for an interesting series of ex- periments in selective breeding. Through such an accidental discovery, Mr. Burbank was able to de- velop two varieties of fragrant verbenas which were introduced under the names of the May- flower and the Elegance. a w Is . -I o ° S- M 03 5 E"0 z£z • t* v &- THE LAWS OF HEREDITY ultimately develop to produce the entire organism with its varied members and bodily organs; but the remaining and essential portion of the germ- plasm maintains its integrity as germ-plasm, di- viding to produce cells of its own kind, even as a bacterium or an ameba divides, and constituting an unbroken series of germ-cells linking the earliest ancestor of any line with the remotest descendant. Parent and child are thus sprung from the same germinal stream, and in the broadest view they are not to be regarded as mother and daugh- ter, but rather as sisters of the same fraternity. The child has the qualities and characteristics of its parent not through any occult law of trans- mission, but because they both draw their qualities from the same germinal stream — the perennial stream of the ancestral germ-plasm. It is important to get this idea of the continuity of the germ-plasm clearly in mind, for it furnishes the clew to a clearer understanding of the mys- teries of heredity than would otherwise be pos- sible. MODIFICATION OF THE GEEM-PLASM It must at the same time be clearly borne in mind, however, that the stream of ancestral germ- plasm, which thus serves as the carrier of heredi- tary capacities from generation to generation, is not entirely beyond the reach of external influ- ence, and does not remain absolutely unmodified throughout indefinite periods of time. [265] LUTHER BURBANK Even the bacterium changes its constitution somewhat in response to the conditions of temper- ature and nutriment in which it finds itself. By altering the medium and thus the food in which bacteria grow, it has been found possible to change their constitution so markedly that viru- lent types become relatively innocuous in the course of a few generations. Recent experiments suggest that the same thing may be accomplished by treating bacteria with ultra-violet rays, not sufficiently intense to destroy their vitality. In a word, very marked modifications in the constitution of the single-celled organism may be produced by altered conditions of its tangible environment. And these modifications are, as a matter of course, passed on to the descendants of the bac- terium, inasmuch as these descendants constitute, essentially, portions of the parent form. Exactly the same thing applies to the allied process of reproduction of the germ-plasm cells of the higher organism. Modified conditions of en- vironment— changed conditions of temperature and of nutrition — may in some cases modify them, and such modifications will be transmitted to their offspring. It is obvious that if such were not the case there could be no change in the structure or con- stitution of any given line of organisms from the remotest ancestor to the most recent descendant, inasmuch as the hereditary and permanent altera- tions of the body-plasm are contingent — accord- [266] THE LAWS OF HEREDITY ing to hypothesis — upon modifications of the germ-plasm. But a& nowadays it is fully admitted that all forms of life have undergone change in the past — higher forms evolving from lower ones through modification — it is obvious that each stream of ancestral germ-plasm must have been more or less subject to influences that modify it. As much as this at least is admitted by every biologist, whatever his view toward the allied question of the heritability of modifications that affect the body-plasm of an individual rather than the germ-plasm — a question, by the way, that will claim our attention in another connection, but which need not becloud our vision at the moment. It must be understood, however, that the modi- fications that can be introduced in the germ- plasm in any given organism, through whatever environmental changes, are relatively slight as contrasted with the totality of qualities of that germ-plasm. It is inconceivable, for example, that the germ- plasm of a brier should be so modified that its offspring will be bearers of grapes; or that the germ-plasm of a thistle shall become so trans- formed that the body-plasm sprouting from it in the next generation shall produce figs — to revert to the familiar illustration with which we set out. To be sure, the vine that bears grapes and the tree that bears figs were doubtless originally as different from their present states as they still are [267] LUTHER BURBANK different from thorns and thistles, but the gradua- tions of modification through^ which the trans- formation has been brought about were infinitesi- mal in any pair of generations and have produced their effects only through the cumulative influ- ence of myriads of generations. If really radical transformations could be wrought in the germ-plasm of any organism in a brief period of time, the whole organic world would be topsy-turvy and there would be no laws of heredity to discuss — at least those laws would be something quite different from what they are. Let us, then, supplement our idea of the con- tinuity of the germ-plasm with the thought that this germ-plasm may be modified from time to time, but that the amount of modification permis- sible within any limited period is infinitesimal in comparison with the sum total of the qualities of the germ-plasm itself ; which qualities, it may be added, represent the aggregate influence of past environments throughout vast and incomprehen- sible periods of time. Luther Burbank has a capital phrase, to the effect that "heredity is the sum of all past envi- ronments." The import of the phrase becomes perhaps clearer if we think of it in connection with this picture of the ancestral germ-plasm — the tangible and definite series of cells directly link- ing every individual of any generation with the entire series of its direct ancestors. [268] THE LAWS OF HEREDITY CHICKEN VERSUS EGG When we consider the germ-plasm in this light, its transmission of hereditary qualities seems in a sense simple and unavoidable. But if we consider the matter a little more at- tentively it will appear that the germ-cell retains no small measure of mysteriousness. We agreed that there was nothing mysterious about the fact that the single-celled organism — say the bac- terium— transmits its qualities, inasmuch as its entire body is bisected. But, although we have likened the germ-cells to a single-celled organism — which in point of fact it externally resembles — we cannot proceed far without noting the vital fact that the germ-cell carries the potentialities not merely of other germ-cells like itself, but of body-cells in endless profusion that go to make up the complex organism — let us say of a tree or of a man. How is it conceivable that a germ-cell of mi- croscopic size shall carry forward such poten- tialities, and carry them so definitely that they predetermine with absolute accuracy the form of every leaf on the tree, or the color of the eyes, the complexion, and the mental qualities of the man? As to that, no one can give a really valid an- swer. That the germ-cell does convey these po- tentialities is familiar matter of fact. How it can convey them seems at first thought absolutely in- comprehensible. But philosophers in all ages have puzzled over the matter, and there have been [269] LUTHER BURBANK various theories put forward in attempted ex- planation. There was, for example, a theory that gained popularity a few centuries ago, to the effect that all the individuals that are to descend (in succes- sive generations) from any given germ-cell exist preformed in that cell. In a figurative sense, this fact might be said to be axiomatic. But the advocates of the theory declared that it was true in a literal sense also. Out of this thought-tangle arose the famous quibble as to which first existed — the chicken or the egg. Of course there was not the slightest scintilla of proof of any such mysterious ingulfing of in- finite numbers of future organisms in the micro- scopic cell. And, equally, of course, the theory did not long persist. MECHANISM OF THE GEKM-CELL Nevertheless, it is interesting to attempt to visualize conditions, even when the conditions themselves lie beyond the limit of microscopic vision. And when the germ-cell is thus visualized, one is forced to conceive of it as made up of in- finitesimal particles of matter that in some way carry preformed the future organism that may grow from it. No one nowadays, however, sup- poses that this aggregation of infinitesimal par- ticles in the germ-cell represents a replica of an adult organism. The conception is merely that [270] THE LAWS OF HEREDITY there are particles of matter to represent each tissue or organ of the future organism, and that these are in some way so mutually disposed as to predetermine the future relations of the organs that will develop from them. The modern physicist makes accurate studies of the sizes of molecules and atoms and of their numbers in a particle of matter comparable to the smallest germ-cell, that enables us to compre- hend how very complex a structure this germ-cell may really be. He tells us, for example, that there lies at the heart of the germ-cell a nucleus of infinitesimal size, yet his microscope reveals various physical structures within the nucleus which he calls "chromosones" because they are readily colored by stains. He believes that these "chromosones" have to do with the transmission of characters, yet he knows that they themselves must be enor- mously complex ; and he makes calculations which show that these chromosones, infinitesimal though they be, are made up of millions of atoms. The very smallest particle of matter that the micro- scope reveals is estimated to contain "many times twenty billion atoms. " So the germ-cell may be in reality an enor- mously complex organism, containing thousands of particles, each one of which is made up of mil- lions of atoms. Such a computation, while it to some extent satisfies the mind as giving tangibility to the sub- ject, does not in any proper sense fathom the [271] LUTHER BURBANK mystery. It shows us that the germ-cell may be indefinitely complex ; but it does not explain to us how its aggregated particles — which themselves are all grouped within the compass of a single microscopic cell — can definitely determine the size and form and color and peculiarities of the future organism into which that cell may grow. In a word, the ultimate mystery of the trans- mission of traits through heredity, which is in- volved in the mystery of every higher organism, is an unsolved enigma which challenges the pro- founder insight of the future investigator. Here we must be content to take the facts of heredity for granted, and to point out the modus operandi of inheritance without attempting to fathom its precise meanings. In a word, the mystery of heredity is linked with the mystery of life itself, and the two mys- teries await a common solution. THE FACTS OF HEEEDITY The facts of heredity, considered in detail, seem enormously intricate, yet they may be re- duced to a few comparatively simple general classes. Indeed, the broad fundamental fact that each organism tends to reproduce its qualities in its offspring may be said to be the one all-com- passing fact that includes every minor detail of hereditary transmission. The full meaning of this great central fact of heredity was perhaps most comprehensively in- 1 272 ] THE LAWS OF HEREDITY terpreted by Professor Ernst Haeckel, when he formulated his so-called "gastraea" theory, in accordance with which each individual organism tends, in the course of its development, to repro- duce the ancestral forms through which the race has passed in its evolutionary progress. Thus the human embryo is at first a single cell and it passes in its embryonic development through stages in which it resembles such lower orders as fish and amphibia and lower mammals before it assumes the proportions and character- istics of the human being. The characters are, of course, slurred over, and the reproduction of racial history is at best a blurred and epitomized one, yet the fact that the embryo does pass through such varied transfor- mations, and that these at least roughly outline the racial history, is a highly interesting and im- portant one, and may be said to exemplify the fundamental law of heredity in the most com- prehensive way. It is obviously a mere detail within this gen- eral law that an adult individual should some- times develop a characteristic or an anomaly of some organ or tissue at the same age when the same characteristic or anomaly was manifested by a parent. Examples in point are furnished by those not familiar cases in which a cancerous growth develops at about the same age in parent and offspring, or in which a mental aberration similarly manifests itself. Such manifestations of heredity are spoken of [273] LUTHER BUKBANK as "homochronous," but the big word scarcely adds anything to the observed facts. The same may be said of the words "homotic" and "heterotopic" heredity, sometimes employed to express the fact that an inherited anomaly — say a tumor — may appear in the same tissues of the body of parent and offspring (homotic), or in another case in different tissues (heterotopic). The fact is, as regards this particular matter, that a tendency to the development of a tumor may be inherited, but that the precise location of the tumor may perhaps be determined by the ex- traneous circumstances — say a local irritation. The inheritance of special abnormalities of a precise and definite character — say a lock of white hair located on a particular part of the head, as a typical example — is likely to arouse surprise and to call forth comment on the mysteries of in- heritance; yet rightly considered such a phenom- enon is no more remarkable than the inheritance of all the ordinary characteristics that lead to what is familiarly spoken of as a family resem- blance. No one is surprised that the eyes or hair or complexion or stature or shape of nose or habits of mind in any individual strikingly resemble the same qualities of the individual's father. In other words, the broad general facts of heredity are accepted as matters of fact without seeming to call for special comment. Stated otherwise, this is no more than saying that no one is surprised that grapes grow on grape vines and [274] THE LAWS OF HEREDITY figs on fig trees. We would be astounded were the conditions reversed; and this evidences the almost axiomatic character of the great funda- mental law of heredity, and its universal accept- ance as a part of common knowledge. MINGLING MODIFIED GEKM-PLASMS In all this, then, we are expositing the idea that the racial germ-plasm conveys the record of past environments and predetermines the char- acteristics and qualities of the organism that may grow from that germ-plasm. As thus far viewed, therefore, the facts connoted in the familiar phrase "like parent, like child " are scarcely more mysterious than the fact that successive cups of water dipped from the same stream should be like one another. But there is a vastly complicating fact which we have thus far purposely ignored — the familiar fact, namely, that each higher organism is not the offshoot of a single parent, but a product of the union of two parents. Be it plant or animal, every individual above the very lowest strata of organic-like owes its being to the union of two germ-cells. It represents the commingling of two strains of racial germ- plasm. Pollen grain unites with ovule in the case of the plant; sperm-cell with ovule in the case of the higher animal; and each type of cell conveys its own coterie of hereditary potentialities. This is the essential and primary fact that com- [275] LUTHER BURBANK plicates the entire situation. The fact of double parentage is one that will be seen at a glance to remove all simplicity from the formula "like pro- duces like." For no two individuals are precisely alike; no two cells of the germ-plasm carry pre- cisely the same ancestral traits. The briefest consideration will suggest some, at least, of the complications that necessarily result when more or less divergent germ-plasms are commingled. Of course, if two ancestral germ-plasms are too widely divergent they cannot commingle at all. The two organisms are then said to be mutually infertile. This was formerly supposed to be the case with most different species. Indeed, the test of capacity to interbreed with the production of fertile offspring was long considered to be the best test of specific identity. Nowadays we know, thanks largely to Mr. Burbank's experiments, that this test cannot be fully relied upon. Never- theless, it is clear that only species that are some- what closely related can interbreed. Even where union takes place between mem- bers of the same species, however, there are sure to be some divergent traits that are more or less in conflict. It may chance even that there are numerous minor traits that are mutually antago- nistic. For example, to take the simplest and most familiar case, animals of the same species may differ radically in color. One guinea-pig may be jet black and another pure white. It is obvious, [276] THE LAWS OF HEREDITY in such a case, that the offspring cannot be like both parents in color. Here, then, is a complication that introduces an element of uncertainty into the otherwise sim- ple law of heredity. It is perhaps not too much to say that all ques- tions of heredity center chiefly around the in- quiry as to just what are the mutual relations of more or less antagonistic qualities when com- mingled through cross-fertilization. HYBRIDIZATION AND VARIATION At an early stage of his work in plant develop- ment, Mr. Burbank discovered that it is possi- ble to hybridize species that are seemingly quite divergent, and that the results are often very striking. He brought together plants from differ- ent continents, and found that in many cases they would interbreed. For example, he hybridized the Siberian rasp- berry with the California dewberry, producing a remarkable new fruit which he called the Primus berry. Everyone is familiar with the conspicuous differences between a raspberry and a blackberry. To mention only one of them, the raspberry leaves its receptacle on the vine when picked, while the blackberry retains the receptacle as part of the fruit. It at once becomes an interesting question as to how these divergent qualities are harmon- ized in hybridized offspring. [277] LUTHER BURBANK In point of fact, inspection of the hybrid Primus berry shows that each parent strove to transmit its own peculiarity as regards this mat- ter of the receptacle. The result is that the Pri- mus berry, if plucked just at the moment when it is approaching maturity, acts like a blackberry, bringing away the receptacle as part of the fruit. But if the fruit is left on the vine until a little past the moment of maturity, it shows the prop- erty of the raspberry, leaving the receptacle on the vine, and coming away as a cup-shaped fruit. Here, then, there is a compromise in which it may be said that each line of ancestral tendencies makes its influence felt. In general, it may be said that this case is typical. As a rule, the different traits of plants or animals that can be interbred are not so widely divergent as to be absolutely antagonistic, and the offspring is likely to show a blending of the traits. There are numerous cases, however, in which a compromise is not so readily effected, and in which one trait or the other seems for the moment to be predominant. As an illustration of this, take the case of Mr. Burbank's white blackberry. If this is crossed with a black blackberry, the hybrid bush will bear only black berries; the tendency of the white blackberry to reproduce itself seems entirely sub- ordinated. But, although for the moment subordinated, the tendency to produce white berries is not lost from the germ-plasm of the hybrid. The proof [278] THE LAWS OF HEREDITY of this is found in the fact that in the next gener- ation a certain proportion of the progeny will bear white berries. This reappearance of a sub- merged trait in the second and in subsequent generations furnishes one of the most striking and interesting aspects of the entire subject of heredity. THE PKODUCTION OF MUTANTS Mr. Burbank had not proceeded far in his studies of hybridization before he discovered that the most astonishing segregation and redistribu- tion of characters may take place in second- generation hybrids. If he crossed two parent strains that were more or less divergent, he might find the traits of the parents variously blended in the hybrids of the first generation ; but if he interbred these hybrids, he was almost sure to get in the next generation a conglomerate fraternity, showing the traits of the grandparental forms reasserted into almost every imaginable combination. More than that, there were likely to appear forms that diverged markedly from either of the grandparents. It would seem that the mingling of divergent germ-plasms had made possible the rejuvenescence of ancestral traits that had long been submerged. Mr. Burbank found that by carefully inbreed- ing individuals that showed the new or revived trait he could accentuate the quality and in many cases produce new varieties so markedly different [279] LUTHER BURBANK from either of the grandparental forms as to jus- tify his use of the term "new creations. " The only plausible explanation of such anom- alies is that the qualities thus newly revealed and accentuated were traits that had been manifested by remote ancestors, but which had been subordi- nated and submerged through conflict with other more or less antagonistic traits in the ancestral germ-plasm. So striking were the modifications that Mr. Burbank was thus enabled to produce at will through the hybridizing of divergent forms that he came to feel confident of being able to modify almost any form of plant life, and produce strik- ing new varieties, provided an allied form could be found with which hybridization could be ef- fected. When the celebrated Amsterdam botanist, Pro- fessor Hugo De Vries, came forward with his theory of mutation, according to which a form of plant life may now and again diverge radically from its parent forms through "spontaneous" variation, constituting a new form of "mutation," Mr. Burbank was first to assert that such mutant forms were explicable as due to hybridization. He asserted that he himself produced muta- tions at will through hybridization, and the long list of his plant developments afforded striking verification of his claim. More than this, Mr. Burbank 's experiments led him to believe that hybridization takes place among plants and animals in a state of nature [280] DWARF CHESTNUT TREE. This reproduction of a direct color-photograph shows a bush-like tree that is a fine example of a Burbank hybrid chestnut. The workman who stands beside the tree is five feet seven inches tall. Note the abundant crop of nuts on the tree and under the tree. Gathering chestnuts becomes a simple matter when the trees are of this type. THE LAWS OF HEREDITY much more commonly than had hitherto been supposed, and that such hybridization is often responsible for the production of new forms that may play an important part in the scheme of evo- lution. He believes, indeed, that hybridization largely accounts for the origin of those variations which Darwin had been content to speak of as "spontaneous," and which are recognized as the material with which natural selection works in developing new species. MENDELIAN HEREDITY The striking results in the production of new varieties through hybridization that Mr. Burbank had attained became known to horticulturists and biologists, and probably had an important share in preparing the world to look with interest on the experiments of the Austro-Silesian monk, Mendel, when the obscure report that this ex- perimenter had published as long ago as 1863 was rediscovered just at the close of the nine- teenth century. Mendel, working chiefly with the garden pea, had paid attention (as we have already seen) to a few conspicuous characters regarding which different races of garden peas differ. He had observed the mutual relations in the inheritance of such qualities as tallness versus shortness of vine, pinkness versus whiteness of flower, yellowness versus greenness of pod, etc., and had traced very definitely and with scientific [281] LUTHER BURBANK precision the relations of these qualities in cross- bred plants of the first and second generations. In so doing he reduced to a definite formula the observation of the mingling of traits in the first generation and their redistribution and recombi- nation in the second, which Mr. Burbank has ob- served to be so common a phenomenon with the great number of species with which he worked. But Mendel went further. He formulated a theory as to the causes that operate to determine the relations of antagonistic characteristics when brought together through the mingling of diver- gent germ-plasms ; and his theory was at once so simple and so satisfactory that it has now come to be accepted at least as a provisional hypothesis everywhere. According to this theory, every tangible char- acteristic of any organism is determined by the mingling in the embryonic germ-plasm of two hereditary "factors" or "determiners," the jux- taposition of which is essential to the production of the character in question. If these factors represent the same quality, there will, of course, be no antagonism, and the quality of the resulting character will not be in doubt. But if, on the other hand, the two factors are antagonistic — one, let us say, representing a black berry and the other a white berry — the result may be that one factor entirely dominates the other, the subordi- nated character seeming to have no representation whatever. But the factor thus submerged reproduces it- [ 282 ] THE LAWS OF HEREDITY self and distributes its representatives in the germ-cells of the next generation quite as freely as does the dominant factor. So there is an even chance that factors of the subordinate type will be represented in the germ-cells that are to pro- duce progeny of a second generation. According to the mere theory of chances, if we mix together indiscriminately a quantity of black factors and white factors in equal numbers, and pick out pairs of factors at random, it must result that in any average group of four pairs we shall find one pair of black factors, one pair of white factors, and two pairs of mixed factors. If you will experiment with checker-men, draw- ing them in pairs from a mixed lot, you will be surprised to find how generally you approximate the formula, even when small numbers are in question. NATURE'S GAME OF CHANCE According to Mendel's interpretation, nature performs such an experiment whenever two germ- cells bearing antagonistic factors have come to- gether, and the results of her game of chance are seen in the phenomena of what have come to be spoken of as Mendelian heredity. Tangibly illustrated, the result is that when, for instance, a pea having a tall vine is crossed with one having a short vine, the offspring will be tall; but their offspring will be represented, on the average, by one tall vine (pure dominant) that will breed absolutely true, one short vine [283] LUTHER BURBANK (pure recessive) that will also breed absolutely true, and two tall vines (mixed) that will not breed true because they contain factors both of tallness and of shortness. The essential truth of the Mendelian formula has been demonstrated by thousands of observa- tions, but a good many workers who have ob- served its application in simple cases have failed to realize the true bearing of the phenomena. The truth seems to be that it is only the comparatively superficial and newly acquired characteristics of any organism that still have sufficient flexibility to be experimented with by nature in this game of chance that we speak of as Mendelian heredity. Stated otherwise, what we term Mendelian inheritance appears to be nature's method of test- ing out new qualities that are from time to time impressed on the organism through the influence of environment. Some individuals of a certain strain of plants or animals chance to be subjected to influences that modify somewhat the color of flowers, the texture of hair, the size of body, or what not. An individual of this modified race presently inter- breeds with an individual not so modified. The important question is this: Is the modi- fication beneficial to the species or otherwise? The matter is put to an impartial test through the operation of Mendelian heredity. All the immediate offspring present tangibly the modified character, but the unmodified char- acter is given a hearing again the next genera- [284] THE LAWS OF HEREDITY tion. And if the modification is neither favorable nor unfavorable to the race, it may chance that two varieties, one showing the modification and the other without it, will continue to flourish in the same environment. As a typical instance — taken at random — you may find gray screech-owls and red ones in the same brood. If, however, the modification is favorable, the individuals possessing it will ultimately prevail over those lacking it, and it will be added to the regular equipment of the species. If, contrari- wise, the unmodified character was better adapted to meet the requirements of environment, it will prevail, and the individuals having the modifica- tion will be weeded out. A pure "recessive," as we have seen, carries no factors for the antagonistic "dominant" qual- ity. Thus it may come about that certain traits of a given organism are absolutely eliminated from the germ-plasm of a fixed proportion of the descendants of that organism. Thus — anomalous though it seem — an individual may be of "pure" strain notwithstanding the fact that one of his grandparents was of different strain; and the known laws of heredity pretty clearly explain the anomaly. This is the one really new conception in the present-day interpretation of the laws of heredity. The older idea was that any trait once impressed on the organism remains forever as a latent char- acter in the germ-plasm, and is susceptible of [285] LUTHER BURBANK being made tangible in some of the progeny under favorable conditions. The laws of Mendelian inheritance show us that the factors of heredity may be so redis- tributed that individuals of the same parentage, and hence precisely the same heredity, broadly speaking, are radically different in their innate hereditary tendencies as regards some minor but perhaps not inconsequential qualities. The new knowledge does not controvert the old rule that "like produces like," but it gives us new insight into the interpretation of that rule. In its practical bearing on the interpretation of heredity as applied to human beings, the new knowledge takes precedence in importance over all that has hitherto been known about heredity. Until the Mendelian interpretation was avail- able, no one could pretend to fathom the mysteries of atavism, much less to predict as to the prob- able recurrence of submerged ancestral qualities in any given generation. But the Mendelian formula serves as a work- ing hypothesis that enables us in many cases to predict with a fair degree of certainty what will be the result of the union of individuals of known heredity. Thanks to this hypothesis, however, the laws of heredity in their application to the human organ- ism now take on a definiteness that they hitherto have lacked. [286] THE LAWS OF HEREDITY MENDELISM AND INSANITY As an illustration in point, let us note the re- sults of some recent studies which give us new light on the heritability of that most pitiable of human afflictions, insanity. It seems to be established that the forms of nervous instability that lay the foundation for insanity tend to act as Mendelian recessives in heredity. It follows that if an insane person is mated with a perfectly normal one, the offspring will probably be personally normal, although carrying the factors of nervous instability in their germ- plasm. But if two individuals having this heri- tage are mated, even though both are personally normal, there will almost certainly be evidence of nervous instability in at least one in four of their offspring. Consideration of the Mendelian formula, which has been fully stated in earlier chapters of this book, makes it clear why the examination of pedigrees, to determine whether heredity enters into the causation of any given case of insanity, must be extended beyond the first generation of the ancestry, and in collateral lines. It will be recalled that a recessive trait makes itself tangibly manifest only when the factors for recessiveness are combined in the germ-plasm, uncomplicated by the presence of the opposite factors ; and hence that the recessive traits always " breed true." This explains the observation of [287] LUTHER BURBANK psychiatrists who report that, in cases under ob- servation, where two persons both of whom are insane are mated their offspring all become in- sane. It is obvious, then, that the question of selec- tion of marriage partners for persons in whose families there is a strain of insanity is a highly important one. Mendelian heredity explains how it is possible that, in a fraternity whose parents were " mixed dominants " as regards the factors for mental instability, one individual may inherit a perfectly sound and normal nervous system, whereas an own brother or sister of this individ- ual— even a twin — may inherit a nervous system so unstable as to invite overthrow. This must be borne in mind whenever we con- sider the question of persons in whose families there are strains of insanity. Unfortunately a recessive trait, in the case of a mixed dominant, may be so completely submerged that it gives no manifestation whatever of its presence. Yet it will come to the surface no less surely if this person marries with another mixed dominant. So the only safe rule in a case where there is known to be insanity in the family heri- tage is to avoid marrying into another family having a like defect. It is obvious that cousin marriages under these circumstances would be peculiarly hazardous. [288] THE LAWS OF HEREDITY BREEDING FOE GENIUS There is, however, another aspect of the sub- ject of cousin marriages that must not be over- looked in the present connection. It is true that such unions involve the danger of accentuating strains of nervous instability in the family through combination ; but it is also true that there is the possibility of accentuating nervous and mental characteristics that underlie genius itself. In point of fact, the old tradition about the affinity between genius and insanity is not alto- gether without foundation. Men of the very highest type of genius, to be sure, are eminently sane; yet it would appear that there are certain attributes of sensitiveness of nervous organiza- tion, tendency to egoism, and almost preter- natural energy that may occur from time to time in a family and may in some instances be com- bined in such a way as to produce genius, while in other instances they induce insanity. To advocate the marriage of cousins in a fam- ily characterized by exceptional qualities of brain would, therefore, be in a sense hazardous, yet it might result directly in the production of men of genius. A very good illustration of the possibility of producing a fraternity of exceptional individuals through the union of cousins who are themselves exceptional is furnished by the pedigree of Fred- erick the Great. In point of fact, this pedigree furnishes a striking illustration of close inbreed- [289] LUTHER BURBANK ing not unlike that which Mr. Burbank practices when he would accentuate a desirable quality in one of his plant families. The case has double interest in the present view because, in consider- ing it, we are brought back to the family of the seven brothers whose practical experiment in eugenic breeding was referred to in an earlier chapter. It will be recalled that of the seven brothers only one married, and that in the succeeding gen- erations the duty of transmitting the family name devolved upon one Ernest Augustus, Bishop of Osnabriick, who married an extraordinary woman, Sophia of Palatine. The child of this union was married to a daughter of the Bishop's brother, and these cousins were the grandparents of Frederick the Great and his distinguished fra- ternity. When a chart showing the full genealogy of this extraordinary family is shown it appears that the father and mother of Frederick the Great were cousins ; that both pairs of his grandparents in turn were cousins ; and that his paternal grand- mother was the sister of his maternal grandfather and cousin of his maternal grandmother. In the third generation, of four pairs of an- cestors, one pair appears in both paternal and maternal strains, so that there are only six per- sons, and two of the six are brothers; there be- ing only five ancestral strains of blood repre- sented, instead of the normal eight. Here, then, is an extraordinary case of inbreed- [290] THE LAWS OF HEREDITY ing, in which are combined the strains of many remarkable individuals; for in addition to those already mentioned the pedigree shows, in the third generation, two other remarkable women, Eleanor d'Olbreuze and Louisa Henrietta of Orange, the latter a descendant of the Great Wil- liam the Silent and the only less celebrated Gas- pard the Second. The blood of William the Silent appears in three other strains of the pedigree, and that of Mary Queen of Scots in two strains. In a word, there is scarcely an undistin- guished male among the forty individuals who represent Frederick's ancestors within five gen- erations ; the fact that these are but forty, instead of the normal sixty-two individuals, in itself re- veals graphically the extent to which the vari- ous strains of this distinguished ancestry are interwoven through an intricate web of inbreed- ing. The progeny of this extraordinary experiment in eugenics reveal, in the generation upon which our attention is focused, not only Frederick II, one of that small select company of all time who by common consent are surnamed "the Great/' but a brother Henry and a sister Amelia almost equally gifted, and a sister, Sophia Ulrica, who may be said to stand fully on a par in intel- lectual endowment with her illustrious brother, and who as Queen of Sweden was known as i ' the Minerva of the North," and became the mother of the famous Gustavus III. [291] LUTHER BURBANK INBEEEDING FOE DEGENEEACY But lest too sweeping a conclusion be drawn from this remarkable example of inbreeding for genius, it is desirable that we should at once turn to another royal pedigree and observe the effects of inbreeding where the traits combined and ac- centuated are not preponderantly desirable ones, as in the case of Frederick the Great, but include also elements of mental aberration and physical and mental degeneracy. Such a pedigree is supplied in the immediate ancestry of Don Carlos, the " madly depraved and cruel" scion of the Spanish royal house, a man who has been characterized as the most heartless and depraved individual in modern history. A glance at a chart showing the ancestry of Don Carlos reveals that his father, Philip II, and his mother, Mary of Portugal, were at once first and second cousins, and that each ancestral strain leads quickly back to ancestors characterized as weak or cruel or mad. Joana "the mad" appears twice in the third generation, and the insane Isabella four times in the fifth generation. The inbreeding is so close and intricate that it would be difficult to characterize the relation- ship. In five generations there are only twenty- eight individuals instead of the normal sixty-two. Thus a profoundly neurotic strain is allowed to become overwhelmingly preponderant by repeti- tion. As Dr. F. A. Woods has said, it was as if [292] THE LAWS OF HEREDITY the sovereigns of that time were breeding mental monstrosities for a bench show. Their experi- ment shows the eugenic principle inverted. But the feature of the pedigree of the de- praved Don Carlos which chiefly concerns us at the moment is the fact that there appear in the table, mingled with the names of the weaklings, the mentally unbalanced, and the morally de- praved, the names of several famous characters, including Charles the Bold of Burgundy, Maxi- milian I of the Holy Roman Empire, Ferdinand and Isabella the Catholics, and the Emperor Charles V. What further excites surprise is that the names of Ferdinand and Isabella appear again and again in the fourth generation, and that in the heritage of Isabella there seems to be an al- ternation of generations between insanity and genius. This gives practical illustration of the affinity — above referred to — between mental aberration and genius of a certain type. It suggests further that genius and mental impairment follow the same law of inheritance. There is a growing body of evidence to show that both views are valid. In recent years investi- gation has been made not only on the bad strains of royal pedigree, but on the heredity of genius and of insanity among people in general, and the result is that we are nearer an understanding of this hitherto obscure subject than ever before. The puzzling thing has always been that the children of the man or woman of genius very [293] LUTHER BURBANK commonly have no genius; yet that they some- times seem able to transmit genius to their descendants. No explanation of this anomaly was forthcom- ing until the recent studies gave a clew through the suggestion that genius is a unit character (or group of traits) which acts in inheritance as a negative or so-called " recessive " character. It is pretty obvious, then, that we cannot al- ways tell just what will be the result when repre- sentatives of families having neurotic strains in- termarry. There may be cases in which it will be difficult to predict as to whether the children will probably be stable geniuses or persons of very unstable nervous system. But as the former are very rare or the latter very common, it follows that the chance of favorable results from a union that thus blends neurotic strains is far from favorable. [294] CHAPTER XIII NURTURE VERSUS NATURE REPORTS have recently come from New Zealand that tell a remarkable story about the Monterey pine. This tree is indigenous to California. It grows in very re- stricted regions, and the comparatively few individual trees that are now in existence are supposed to be reminiscent of a remote prehis- toric flora. Indeed, the chief interest of the tree hitherto has been the fact that it is found in so restricted an area, and in such small numbers. But now word comes from New Zealand that this tree has proved to have very remarkable qualities when grown in that country. Someone made the experiment of transporting the Monte- rey pine to New Zealand a good many years ago, and this change of environment appears to have had a most extraordinary effect. Whereas the Monterey pine in its native coun- try is practically valueless from an economic standpoint, it proves so remarkable a producer of wood in its new home that it has there received the name "The Wonderful Tree." Reports tell us that the Monterey pine in this new habitat exceeds all other trees in rapidity of [295] LUTHER BURBANK growth, and produces an amount of valuable lumber that is quite without precedent. No species of pine in America produces lum- ber at a rate at all comparable to the records that come to us from New Zealand, telling of the extraordinary productivity of the Monterey pine, which in its native climate is of such slow growth and produces timber of such poor quality that it is not usually listed among timber-producing trees of economic value. Now it is obvious that the transplantation of the Monterey pine from California to New Zea- land can in no wise have affected the hereditary tendencies of the tree. Whatever capacities for growth and timber production are revealed by the tree in New Zealand must have existed as poten- tial qualities in the seed that was taken to New Zealand from California. The change has not been brought about from hybridization or by selective breeding. It is merely that a new environment — new soil, different climate — has taken a hand in the de- velopment of the submerged hereditary factors; and under these new influences the tree has been made to reveal possibilities that were hitherto un- suspected. So the case of the Monterey pine affords a very striking demonstration of the influence of en- vironment in bringing out unsuspected hereditary tendencies. It furnishes an object lesson in the power of nurture to supplement — and even, on [296] HYBRID MASSACHUSETTS ELM OX CAL ROOTS Note the different quality of bark at the base of the tree, representing the California stock, on which the twig brought from Massachusetts was grafted. The tree is only fifteen years old, and its extraordinarily rapid growth is ascribed by Mr. Burbank to the fact that the parent from which the twig was cut was a natural hybrid. NURTURE VERSUS NATURE occasion, seemingly to supplant — the power of nature. AN IMMIGEANT BHUBARB But this very striking demonstration of the modifications in the life history of an organism that may be brought about through changed en- vironment is by no means without precedent. Something quite comparable has been ob- served, for example, when the migration has been effected in the opposite direction, the plant being brought from the southern hemisphere to our own northern latitudes. The case of the eucalyptus tree, which takes on extraordinary capacities of growth in Califor- nia, is perhaps not to be too greatly emphasized because this tree is also a rapid grower in its native Australian soil. But there are other plants that seem to reveal new possibilities, in particular when brought to California from the southern hemisphere. As a typical instance, we may recall Mr. Bur- bank's winter rhubarb. This plant, when Mr. Burbank first imported it from Australia, had a stalk scarcely larger than a lead pencil. The sole value of the plant from an economic standpoint, and the thing that gave it chief interest for Mr. Burbank, was the fact that it had the habit of put- ting forth stalks in cold weather. Lower temperature appeared to have the effect of stimulating it, just as high temperatures stimu- late most other vegetables. [297] LUTHER BURBANK Mr. Burbank saw in this peculiar habit the pos- sibility of producing a valuable market vegetable that would mature at times when the ordinary pie-plant is dormant. The expectation was veri- fied. Under the changed environmental condi- tions of California, the winter rhubarb developed wonderfully, without hybridization, until its stalk was many times larger than the original plant from the antipodes. Meantime it retained its habit of putting forth stalks most abundantly dur- ing the period of cold weather. But of course the winter season in California corresponds with the summer in Australia. So in putting forth its stalks in cold weather at Santa Rosa the plant was modifying its habit radically, as tested by the calendar. That is to say, it now puts forth its stalks in response to the stimulus of cold weather from November to January, instead of from June to August. Here, then, was a case in which changed con- ditions of the environment, as marked by the most radical shift of seasons, sufficed to transpose the time of bearing of the plant, twisting it an en- tire half-year out of reckoning. But meantime the hereditary clockwork mech- anism within the cells of the plant, through which its time of development had been adjusted for the months of June, July, and August, still main- tained its force; so the plant, thanks to this in- herent impulse — and now operating in defiance of environing conditions — continued to put forth its stalks abundantly at its accustomed time, which [298] NURTURE VERSUS NATURE now, under the changed conditions, coincides with the summer season. The net result of these two sets of impulses was that the plant continued to be a "winter rhu- barb, ' ' yet was now a ' ' summer rhubarb ' ' as well. And by selecting for a few generations among the plants that showed greatest tendency to pro- long the seasons, Mr. Burbank was able to merge winter bearing and summer bearing, bridging the gaps of spring and autumn, until his perfected plant, while he still designated it as a "winter rhubarb/ ' was in reality practically an all-the- year bearer. Meanwhile, by further selection, aided now by hybridization, it was found possible, thanks largely to the aid of the new environment, to stimulate the plant to such unwonted vigor of growth that the descendant of a plant which came to California with a pencil-sized stalk now pro- duced a stalk comparable rather to a broom- handle, lifting its leaves several feet into the air, and fully meriting the name of Giant Winter Rhubarb. ENVIRONMENT VEKSUS HEEEDITY Here again, obviously, we are given a striking illustration of the power of environment to bring out concealed hereditary potentialities. We dare not suggest that environment has introduced new traits that did not exist in the hereditary mechan- ism of the plant. To suggest this would be to im- [299] LUTHER BURBANK ply that environment may transform an organism in a single generation in a way so radical as to bid defiance to specific bounds; making the se- quence of evolution a haphazard performance which we cannot believe compatible with the or- derly progress of nature. We are bound to believe, then, that when we see a plant transformed as to its tangible proper- ties in a single generation, or in a few generations, through the influence of changed environment, we are witnessing the bringing out of suppressed tendencies, the realization of submerged poten- tialities, rather than the implantation and de- velopment of really new traits. Making the interpretation specific, we must believe that the Monterey pine, which now in California is a tree of stunted growth, had an- cestors that were rapid-growing mammoth trees. Through unfavorable conditions — the result, per- haps, of a glacial epoch — the tree gradually modi- fied its habits of growth and perhaps preserved its life through such modification ; but the heredi- tary factors for gigantic growth still existed in its germ-plasm, and awaited only a favorable opportunity to make themselves again manifest. The opportunity came when some chance seeds of the tree were transported to New Zealand, where it chanced that the conditions of soil and climate were such as to favor these long-submerged hereditary factors, giving them opportunity to prove their existence and their latent potentiali- ties for development. [300] NURTURE VERSUS NATURE Similarly the small winter rhubarb, with its pencil-like stalks, as Mr. Burbank found it in Aus- tralia, must be regarded as the dwarfed descend- ant of some tropical plant of the elder day which had been forced to modify its manner of growth to meet altered conditions of climate, but which retained in its germ-plasm, even as the Monterey pine retained, the factors for relatively gigantic growth, biding their time and ready to make re- sponse to altered conditions of nurture. Their opportunity came when seeds of the plant were brought from the antipodes to California, just as the opportunity of the submerged factors of the Monterey- pine was found when the migra- tion was made in the opposite direction. AN EXAMPLE FEOM THE ANIMAL WOELD Were anyone disposed to doubt the validity of this interpretation, to question whether environ- ment has in reality such wonderful capacity to alter the seeming mandates of heredity, evidence in substantiation may be found in quite different fields. Take, for example, the very familiar case of the worker bee. This insect, as is well known, is an immature and sterile female. Under normal con- ditions in the hive, there are thousands of eggs, each like all the others, and each destined to de- velop into a sterile worker. But on occasion the mature workers in the hive enlarge the cell in which one of these worker eggs [301] LUTHER BURBANK is deposited, and feed the larva which hatches from it with an unusual quantity of food of excep- tional richness. And the individual larva thus singled out for exceptional nurture grows and develops at a rate disproportionate to that of its fellows, and ultimately matures and becomes a fertile female, which, in the terminology of the apiary, is designated a queen. This mature individual presently goes forth from the hive with a band of followers, and es- tablishes a new colony. She in turn deposits eggs and becomes the mother of another swarm of drones and workers. Yet nothing is more certain than that the hered- itary potentialities of the egg which thus was transformed into a queen bee were in no wise different from the potentialities of the thousands of other eggs about it that developed only into sterile workers. Nurture alone determined the transformation. In this case it was purely a matter of food. There was no climatic change invoked or needed. Feeding alone sufficed to bring about a final development of the reproduc- tive organs that was denied all the other larvae of the colony. This case of the bee is so familiar that its won- derful significance is often overlooked. Taken by itself, it suffices to illustrate the over- mastering power of nurture to decide among the conflicting hereditary tendencies that lie dormant in the germ-cell. Lest the case seem to prove too much, however, [302] NURTURE VERSUS NATURE let us not forget that it is only the eggs of the worker that through such treatment can be de- veloped into queens. There are also in the normal hive other eggs, produced parthenogenetically, which will develop into male or drone bees, and which can by no possibilities of altered nutrition be transformed into workers or queens, any more than the worker eggs could be made to develop into drones. But this illustration, after all, serves only to give recognition to the fundamental fact that heredity, in the last analysis, puts certain definite limitations on environmental interference. No conceivable environing conditions can be expected, in the nature of the case, to bring out potentialities that do not exist. A dwarfed Mon- terey pine may be transformed through altered nurture into a mammoth pine ; a dwarfed rhubarb into a giant rhubarb ; a worker bee into a queen bee. But no conceivable modification of nurture could transform the Monterey pine into a rhubarb of any sort, or the rhubarb into a pine, or either pine or rhubarb into a bee. To suggest such transformation would be grotesque. Yet these extreme cases are perhaps worth citing to emphasize the fact that when we speak of the power of nurture over nature — as applied to any given individual — we refer only to a power of selection between divergent hereditary tendencies. The pine has become a pine through endless generations of development; the rhubarb has be- [303] LUTHER BURBANK come a rhubarb, and the bee has become a bee, through the same slow process of evolution. Each of these organisms, and every other spe- cific organism of all the myriads, has its own con- geries of hereditary factors, and by no conceiv- able influence can these be suddenly transformed. What has been developed through the slow process of the ages can be modified through a similar slow process of future ages. Yet within each organism, by virtue of the slow development and modification through the past ages, there are stored up multitudes of hereditary factors that are more or less in antagonism, only one or an- other series of which can be made manifest in a given generation. And the power of environ- ment is exercised in selecting between or among these conflicting factors. Nurture could not determine that the Monte- rey pine should cease to be a pine, but it could de- termine whether it should be a dwarf or a giant. Nurture could transform a worker into a queen, but not into a drone. The illustrations from the vegetable and ani- mal worlds have been used to make the case tangible. Let us now turn attention to the human organism, and study the application of this prin- ciple to the development of the human child. THE PEINCIPLES OP EUGENICS When the word "eugenics" first came before the public a few years ago, there were strong ob- [304] A FINE SPECIMEN OF THE ROYAL WALNUT This new Bin-bank variety was produced by crossing the Eastern and Western black walnuts. It grows to exti-aordinary size in a relatively short period. The specimen here shown is only fifteen years old. NURTURE VERSUS NATURE jections to its supposed implications, on senti- mental grounds. Much of the opposition has died away in re- cent years, showing a very remarkable modifica- tion of public sentiment. But even now it is not unusual to hear the feasibility of any attempted application of eugenic principles challenged, on the ground that nature, having been in the busi- ness of matchmaking from time immemorial, is very well able to carry on this business without interference from the scientific students of heredity. Such objections are reminiscent of the thought of an elder day, when the current phrase about marriage being made in heaven was taken more than half seriously, and when the entire attitude of mind of the public toward the question of the relations of the sexes was far more puritanical than it is at present. Many causes have conspired to change public sentiment; and the very fact that the name "eugenics" has made its way so rapidly proves that the intelligent moiety of the public has be- come prepared to give recognition to the idea that man may conceivably exercise a directive influ- ence in the breeding of his own race such as he has all along exercised in the breeding of the animals that he has domesticated. The argument that nature herself is the ideal matchmaker is seen on the slightest critical in- spection to be utterly fallacious; in particular since it has come to be known that hundreds of [305] LUTHER BURBANK thousands of children are born into the world foredoomed to disease or to defective mentality by the mismating of their parents. In the older conception, heredity was fatalistic. So long as it was believed that all the character- istics of a parent are transmitted to all his chil- dren, it seemed inevitable that the sins of the parents must be visited upon the children, in strict accordance with the biblical mandate. But the new knowledge of Mendelian heredity makes it clear that the hereditary factors in the germ- plasm of an individual may be potent or impotent in their tangible influence on the next generation, according to the combinations that are made with the hereditary factors of the other parent. We have seen, for example, that factors for mental deficiency or for susceptibility to consump- tion, even though present in the germ-plasm of an individual, may be utterly unable to make themselves tangibly manifest if that individual mates with one in whose germ-plasm the factors for normal mentality only and for resistance to consumption are present. Thus the mandate that seemed to condemn the offspring may in many cases be rendered nuga- tory by the right selection of marriage partners. Here, then, is a specific instance in which a definite knowledge of the laws of heredity might serve to determine whether the offspring of an individual should be normal or defective; where, in a word, the principles of eugenics might be practically applied with benefit to a fraternity of [306] NURTURE VERSUS NATURE individuals. And if it be objected that such an application of cold scientific principles seems to rob marriage of all romance, it is perhaps an adequate and comprehensive answer to point out, as I have been moved to do on various occasions, that there is nothing appealingly romantic about a brood of epileptic or neurotic or imbecile children. It is possible, however, to supplement this sug- gestion with the assurance that, in general, the ap- plication of eugenic principles to the mating of human beings would not by any means necessitate the supplanting of the old traditional method of matchmaking, but would only serve as a supple- mentary procedure, aimed at the perfecting of a method which must be admitted to lack something of the ideal. NATURE AS EUGENTST In point of fact, it requires but the most casual knowledge of the subject to convince one that nature herself is the original eugenist, and that the motives that actuate individuals under the spell of the god of love are essentially eugenic motives. To substantiate this suggestion, it is only nec- essary to call attention to the fact expressed by the common saying that opposites attract. This means that a person is drawn toward one of the opposite sex whose predominating tendencies cor- respond to his subordinated ones. [307] LUTHER BURBANK Note, as practical illustrations, how the tall man is attracted by the small woman, blonde by brunette, genius by mediocrity. It is even matter of common experience that the most virtuous young women are often fascinated by opposite moral traits in their male associates; while, con- trariwise, the most vicious men would always choose virtuous helpmates if they could. These propensities have long been recognized, and they have been explained as representing a tendency of nature to avoid extremes and keep near to a happy mean. It has been observed that extreme development in any direction leads to in- stability, and -it is everywhere accepted that a well-rounded development is, on the average, preferable to a highly specialized development in one direction. But the real significance of the observed tendency of opposite physiques and temperaments to attract each other is more clearly explicable than ever before since a knowl- edge of Mendelian heredity has given clews to its true interpretation. The fact seems to be that what we term Men- delian heredity represents nature's incessant at- tempt to improve the race. It is an observed fact that physical strength and vigor are dominant factors; hence the off- spring of a strong individual and a feeble one are likely to be strong. It is obviously desirable, then, from a eugenic standpoint, that weak individuals, if they are to mate at all, should mate with strong ones. And nature has all along provided that this [308] NURTURE VERSUS NATURE should take place, through establishing the nat- ural affinity of weak for strong and of strong for weak, just referred to. It is matter of everyday observation that women of a masculine type are attracted to more or less effeminate men; and, contrariwise, that men of the most virile type are drawn to women who are the embodiment of femininity. And the most coldly logical student of scientific eugenics must applaud these inherent preferences. In a word, then, it may be said that the new science of eugenics does not come forward as a revolutionary force, but only as a supplementary force. In general, the study of scientific heredity has sufficed to show the logicality of spontaneous love, rather than to suggest its illogicality. But this verdict must be modified to the extent of urg- ing that it may be possible for the student of heredity to point out individual instances in which a scientific analysis reveals impediments to what otherwise might be a thoroughly eugenic and de- sirable mating. In other words, the province of eugenics at the present stage of its development is, as has been suggested in an earlier chapter, not so much to determine whom an individual should marry as to show, on occasion, whom he or she should not marry. The definite implications and applica- tions of this principle will appear as we proceed. A clew to them is given in the statement that eu- genics is recognized as having two quite different aspects, a negative and a positive aspect. [309] LUTHER BURBANK Negative eugenics aims to prevent the birth of the unfit; positive eugenics aims to bring about the birth of the fit. We must consider each of these subjects inde- pendently, but.it may fairly be said at the outset that negative eugenics has far wider present-day application and is of more immediately practical import to our race than positive eugenics. THE BREEDING OF THE UNFIT It is a familiar observation everywhere to-day that the better classes of citizens as a rule have fewer children than the less desirable classes. A striking illustration of this is furnished by some statistics recently collected by Professor Cattell, of Columbia University, showing that the families of a large number of the more distin- guished scientific men in America consist, on the average, of less than two members. And this ob- servation is fairly in accord with the general observation, according to which the members of the community that should be looked to, from a eugenic standpoint, to propagate the species are the ones who have the smallest families. Contrariwise, it is matter of equally familiar observation that the people of the slums of our cities, the recent immigrants representing the lower orders of European population, and the de- fective and criminal classes, are vigorous and prolific breeders. This, obviously, amounts to saying that in- [310] NURTURE VERSUS NATURE crease of population is largely promoted by the less desirable, rather than by the more desirable, members of the community. Whereas all evolutionary progress in the past has been due, we are led to believe, largely to natural selection of the fittest members of the animal and vegetable populations as the propa- gators of the species, mankind is now making the experiment of artificial selection, in which the survival of the unfit becomes the outstanding feature. It is as if Mr. Burbank were to select among cross-bred plants the ones that showed the least desirable qualities, and were carefully to preserve the seed of these, destroying the seed of the more desirable members of the colony. It needs no profound knowledge of plant breeding to predict what must come to pass were this plan to be fol- lowed in the orchard or field or garden. No one will for a moment suppose that Mr. Burbank could have produced his remarkable new varieties of plants by such a method. No one doubts that the application of such a method would result in the rapid retrogression of even the best varieties, so that they would presently be represented by a degenerate progeny. It is equally little in doubt that a breeder of thoroughbred horses, or of special varieties of dogs or chickens or pigeons, would work havoc in the ranks of his pedigreed stock were he to en- courage the breeding of inferior members and re- strict the breeding of superior ones. [311] LUTHER BURBANK No one doubts that the same laws of heredity apply to plants, to animals, and to the human race. How, then, can we doubt that the present customs of human society, in which the less fit members of the community are by far the most prolific, must tend to encourage racial degenera- tion? Seemingly there can be no difference of opin- ion on this question. But serious differences arise when we proceed to the natural inquiry as to what may best be done to change the existing condi- tions. The statement that it is desirable to increase the prolificness of the better classes and to restrict the fecundity of the inferior and defective classes, considered as an abstract proposition, will pass unchallenged. But whenever the attempt is made to suggest specific means through which these ends may be attained, such suggestions are sure to be met with violent opposition. Nevertheless, it is incumbent upon us, in the present connection, to endeavor to view the situa- tion without sentimentality, and from the stand- point of the student of heredity. In particular, we are called upon to make application, as best we may, of the principles of plant development that are revealed by a study of Mr. Burbank's work, in their bearing on the breeding of the human plant. And when we view the matter from this standpoint, it would appear that there are at least a few specific propositions [312] •ifc^Ml/.,, ^ a, a o ^ 0 O) d) NURTURE VERSUS NATURE that may be urged with a fair measure of assur- ance. EESTKICTING THE FECUNDITY OF THE UNFIT First and foremost among these is the belief that the notoriously unfit members of the com- munity, as represented by criminals, the insane, and the mentally defective, should on no account be permitted to have progeny. These defectives represent a recessive element in the human germ-plasm. And all our modern studies make it increasingly clear how difficult it is to eliminate a recessive trait from the strains of any race of organisms. To be sure, a recessive quality disappears altogether in the first filial generation when mingled in the germ-plasm with the antagonistic and dominant quality. But it not only reappears tangibly in a certain proportion of the offspring of the second generation, but it also remains as a latent factor in the germ-plasm of two out of three of the progeny of that genera- tion who give no outward evidence of its presence. Such, it will be recalled, is the characteristic feature of Mendelian inheritance, and when we consider the facts from the present point of view, it might fairly be questioned whether the terms dominant and recessive might not better have been reversed. It is far easier to fix a recessive quality, because its tangible manifestation proves the absence of the corresponding dominant fac- tors. But we have no way of telling that any or- [313] LUTHER BURBANK ganism showing a dominant quality does not carry the opposite recessive factors dormant in its germ-plasm. So far as we can judge, there is no limit to the number of generations through which the fac- tors for a recessive quality may be conveyed in a state of latency or impotence, and yet may become active and make themselves manifest through a chance mingling with germ-plasm conveying simi- lar recessive factors in the same state of latency. If I correctly understand the matter, recessive characters are characters that are relatively old in the evolutionary sense, and dominant char- acters are those that are relatively new. In each and every case where antagonistic qualities are matched against each other there is reason to believe that the newer character will tend to mani- fest the phenomena of dominance, and the older character the phenomena of recessiveness.1 The entire Mendelian formula might be said to express nature's receptiveness toward innova- tion, on one hand, and her tendency to hold fast to that which has been proved good, on the other hand. An organism that has acquired a new char- 1 Perhaps it should be explained that this interpretation of the underlying nature of the phenomena of dominance and recessive- ness is original with the writer. It is based on a rather wide study of the phenomena of Mendelian heredity in both vegetable and animal worlds. It exactly reverses the explanation that has been suggested by some other biologists, but the writer believes that it is the most plausible interpretation of the phenomena in question hitherto suggested. The basis for this belief will be else- where set forth in detail. [314] NURTURE VERSUS NATURE acter mates with an organism in which the same character is of an older type. The progeny all give outward manifestation of the new character. But their progeny show the recurrence of the old character in one case in four, and two other mem- bers of the four carry the factors for this quality as a recessive element in their germ-plasm. If the new character is beneficial to the species, the individuals showing it (who in the second genera- tion, it will be recalled, outnumbered their fel- lows of the same fraternity three to one) will thrive and propagate their kind, and the individ- uals having the new quality will increase rapidly in number. But meantime there is always a possibility that the new character may be beneficial only under local conditions or for a limited period ; so nature is by no means minded to renounce the old char- acter all at once. Generation after generation, she provides that the factors for the recessive traits shall be carried forward, and that a certain proportion of the individuals of each generation shall be " mixed dominants," whose offspring will have representatives showing the old character. So even when the new character is a highly bene- ficial one, the old character still tends to recur and to fight for recognition. But if, on the other hand, the new character is one that is not beneficial, the individuals that show it are quickly weeded out, and only the re- cessive members of the fraternity remain. In other words, a new or dominant character must be [315] LUTHER BURBANK advantageous to its possessor — or at all events not detrimental — or it is quickly eliminated, be- cause there is no such thing as the carrying for- ward of this character as a latent element in the germ-plasm. But the old and therefore recessive character may be carried forward in the germ- plasm generation after generation, for the very reason that it is not outwardly manifested, and therefore does not handicap the individual in whose germ-plasm it rests. Now we have seen that certain notable defects of the human organism, which are manifested in mental deficiency or insanity, act as recessive traits in inheritance. The same thing is true of the allied defects that are the foundation of crimi- nality. We are led to infer, then, that these con- ditions of mental and moral obliquity represent earlier stages of human evolution. The individ- uals who manifest these defects in any given gen- eration are those whose ancestors have mated in such an unfortunate way as to preserve the re- cessive character either as a patent or a latent factor in their germ-plasm. In effect, the men- tally and morally deficient classes of to-day be- long to a remote generation of the past. The hereditary factors that are responsible for their mental equipment have come down unchanged from remote ancestors who lived under conditions of barbarism in which the traits that we now de- scribe as aberrant or defective were a part of the normal equipment of the race. In the long stretch of intervening generations, [316] NURTURE VERSUS NATURE new traits have been developed and old traits modified, but these traits, which represent the higher attributes of our mental and moral na- tures, while they have proved dominant to the older barbaric traits, have not been able to elimi- nate the old traits altogether from the germ-plasm of the race. So now and again there appears an individual in which the recessive traits are patent ; and it merely evidences the force of the laws of Mendelian heredity with which we have become familiar to note that these recessive individuals breed true to their recessive quality of mental and moral deficiency. Theoretically, we should expect that when two of these recessives are mated, their offspring would be recessives. And the observations of the alienists and crim- inologists in recent years prove the correctness of the preconception. When two mental defec- tives are mated, their offspring are all defectives. Of course we can momentarily submerge the de- fective strain by mating the recessive individual with a normal individual. But the progeny all carry, submerged in their germ-plasm, the re- cessive factors. Even though themselves out- wardly normal, they represent tainted stock, and the taint will make itself manifest sooner or later in their progeny.1 1 The question may arise as why genius may also act as a recessive trait, as previously pointed out. The answer is that the type of genius that may so operate in heredity is the unstable of ill-balanced type allied to insanity, and owing its success largely [317] LUTHER BURBANK Logically, then, there would seem to be no reason why such tainting of a stock should be knowingly permitted. There would seem to be no reason why a recessive individual of this type should be permitted to vitiate the germ-plasm of the race. So long as the recessive quality is latent, we can do nothing directly to eliminate it ; but when it becomes patent in an individual case, opportunity is afforded to dam back permanently that particular stream of recessive germ-plasm. And the way in which this can be effected, obviously, is by sterilization of the individual who manifests the defect. Still holding to the biological point of view, there would seem to be no question that a proper regard for the welfare of future generations de- mands that all mentally and morally defective in- dividuals of unequivocal type should be sterilized. The rule should apply, it would seem, to all sub- normal children ; to the insane of every type ; and to all persons whose lack of moral control is such as to have led them to commit infractions of the social order that rank as felonies. So comprehensive a programme for the elimi- nation of recessive germinal factors for mental and moral traits will doubtless seem little less than appalling to many readers. But there seems to the presence of an elemental egoism and excessive energy that are primordial traits. Stable genius probably tends to be dominant in heredity. The offspring of men of large and stable mental en- dowment are usually able. The sons of Charles Darwin may be cited in illustration. [318] NURTURE VERSUS NATURE no escape from the conclusion that such a restric- tive programme would be of enormous benefit to the coming generations. The lessons of heredity are futile unless we are prepared to act upon them. And there is no reason why action should stop with halfway measures in regard to the classes just named. The imbecile, the insane per- son, and the criminal are undesirable progenitors of members of a civilized community. In the in- terests of the community they should be scien- tifically restrained from incurring the obligations of parenthood. That, seemingly, is the first and perhaps the most unequivocal lesson in negative eugenics that may be drawn from the modern studies of heredity. THE QUESTION OF RESTRICTING MARRIAGES When we turn to the other aspect of the sub- ject that has been most widely exploited — the question, namely, of putting legal restrictions on the marriage of persons suffering from various diseases — we find ourselves on much more debat- able ground. Some rather plausible laws have been put on the statute books of various states in the past two or three years, making it obligatory for persons seeking a marriage license to show a medical certificate giving them a clean bill of health with regard to one or two transmissible diseases. The [319] LUTHER BURBANK purpose of such laws is obviously commendable, but it may seriously be doubted whether public opinion has yet been educated to the point where it will give the laws adequate support. We have advanced a long way in recent years, but there is still a large measure of reticence regarding the discussion of topics directly involved in measures of this character. The futility of attempting to prevent the union of young persons who have decided to marry is matter of common knowledge. Moreover, a really comprehensive law that pre- vented the marriage of all incompetents would fail of its ultimate object, in that it would mainly result in substituting illegitimate children for legitimate ones. As regards the commendable attempt to restrict the dissemination of venereal diseases, which is the essential motive of the laws just cited, it seems probable that this end would be more ad- vantageously effected by comprehensive sanitary laws placing all venereal diseases on a par with other contagious maladies; requiring all cases of such diseases to be reported to the health boards, and inflicting severe penalties on all persons who knowingly transmit these diseases. Such a sanitary code would obviously be diffi- cult of carrying out, but the great strides that public hygiene has made in recent years warrant the hope that such measures as those just sug- gested will before long be thought worthy of trial everywhere. It seems more logical to endeavor to stamp out these virulently contagious and [320] NURTURE VERSUS NATURE heritable maladies at their source than merely to attempt to guard a single avenue among many through which they may be transmitted. Nevertheless, the placing on the statute books of several states of laws of the character just noted may be taken as marking a very notable stage in the progress of the eugenic propaganda. POSITIVE EUGENICS All the measures thus far suggested obviously look to the restriction of the breeding of the unfit, arid leave quite untouched the converse side of the problem — namely, the stimulation of the re- productive activities of the fit. But we have al- ready called attention to the familiar fact that there is a great dearth of children among pre- cisely the classes who are best adapted, through heredity and through the environment that their homes supply, to furnish desirable citizens of the next generation. It is obvious, however, that any attempt to regulate the size of the families of the better classes of society lies far beyond the bounds of present-day legislation. The time may come when special bonuses will be offered in the way of ex- emption from taxation or direct government sub- sidy for large families. Such an expedient is not without historical precedent. But it may safely be predicted that if it should ever seem necessary to resort to so extreme a measure in any civilized community of the future, the provision will not [321] LUTHER BUKBANK be indiscriminate in its application, but will apply to a restricted portion of the community, the favored couples being such as adequately meet conditions imposed by a eugenic board having a fuller knowledge of heredity, perhaps, than any- one at present possesses. Materials for such enhanced knowledge are being gathered, however, by the Eugenics Record Office at Cold Spring Harbor, and it is within the possibilities that enough family genealogies, col- lated from a new point of view, will be available in the course of another decade or two to give data for a new type of pedigreed-stock book, of which human beings will be the subjects. Such a suggestion probably seems grotesque to the average reader ; even to the reader who has gained a certain inkling of the laws of heredity. Yet a serious consideration of the facts as to the increase of population in recent decades, coupled with reflections on the character of the increase, justifies the prediction that legislative measures based on such knowledge will furnish the basis for marriage customs that will become a matter of everyday routine in the not very distant future. We hear much clamor about race suicide; and when a nation like France fails to increase in population as rapidly as its neighbors, the wise- acres shake their heads and talk about national degeneracy. Yet it is known that the population of Christendom has doubled in the past half -cen- tury, and it is a matter of the simplest computa- tion to show that if this rate of increase were to [322] NURTURE VERSUS NATURE continue there would not be standing room in the world for the human population in the year 4000 A.D. If the population of the United States were to increase as rapidly in the coming century as it has in the past century, starvation would stare the main body of our great-grandchildren in the face. In a word, the great menace of the moment is not race suicide but race repletion. And, as we have seen, it is the less desirable members of the race who are most prolific. Hence the human garden is in danger of being choked with human weeds. There is eminent need of cultivation akin to that which Mr. Burbank prac- tices when he would improve a race of plants instead of allowing them to run wild and deteriorate. Yet, as I said before, it must be admitted that at the present stage of social development no very definite remedies, on the side of positive eu- genics, can be suggested as capable of immediate application. The most that can be hoped, per- haps, is that knowledge of the laws of heredity may be spread broadcast, until the average in- telligent citizen is sufficiently informed to have logical opinions on this most important topic. When the time comes that a larger number of cultivated men and women have as comprehensive a knowledge of heredity as is now possessed by a small number of breeders of plants and special types of domesticated animals, and when the public at large realizes that the same laws of heredity apply to man as to all his fellow-beings, [323] LUTHER BURBANK we shall be prepared to consider the possibility of measures looking to the betterment of the human breed through conscious direction of a character not very different from that which has resulted in the development of specialized races of horses and cattle and others of man's confreres. Incidentally, we may add that it is largely with the thought of aiding in the promulgation of knowledge that must underlie such an advance that the present chapters are included in this book. THE PBOVINCE OP EUTHENTCS In the meantime, it fortunately chances that the obverse side of the question of breeding a better race can be considered with far less infringement on the prejudices of mankind in general; partly because the questions involved are not at first thought recognized as having eugenic significance. Eeference is made, of course, to the active move- ments of recent years in the way of bettering the environment of the individuals and the communi- ties of our generation. The work that has already been accomplished in this regard is little less than revolutionary. Its effects must be strikingly manifest on the coming generations. It is unnecessary here to refer, except in the most general way, to the sanitary reforms in question. Everyone knows something of the en- heartening story of how light is being let into the dark tenement dwellings of our cities; how sani- tary guard is now kept over the food supplies, in- [324] NURTURE VERSUS NATURE eluding in particular the all-essential milk supply; how preventive medicine has learned to guard our ports against the invasion of plagues and to minimize the spread of the contagious maladies by warring upon the mosquitoes and flies and rats that serve as germ-carriers. It is familiar knowledge, also, that medical science has found means to treat individuals suf- fering from contagious maladies, and in particu- lar to give immunity to others through serum and vaccine treatments, the discovery of which has resulted from the new knowledge of bac- teriology. All in all, the work of preventive medicine has been so effectively carried forward that the death rate in our cities has decreased, particularly as it concerns the infant population, to a fraction of what it was. The average age of mankind has been practically doubled since the time of our grandparents. All this is matter for just pride and enthusiasm to the humanitarian. Yet from the standpoint of the eugenist, it appears that these triumphs of preventive medicine do not represent an alto- gether unmixed blessing. Looked at with a coldly analytical eye, it appears that the preservation of weakly infants through what may be likened to a hothouse cultivation must enhance the num- ber of adult members of the population of the coming decades who are peculiarly unfit to propa- gate the species. In other words, it would appear that the first [325] LUTHER BURBANK notable result of the recent betterment in the practice of euthenics must be to complicate the problem of the eugenist. From the present standpoint, we could hardly fail to recall that the work of the modern hygien- ist is directly in opposition to the method that Mr. Burbank has so persistently practiced at Santa Rosa in dealing with the weakly and susceptible members of his plant colonies. From the outset, the theory on which he has worked, and worked to such advantage, has been that the best protection to his plant charges against the disease with which they are menaced must come from within the constitution of the plants themselves. So he has sought to develop immune races. He has not been sedulous to find remedies for plant diseases, and he has almost totally avoided the use of sprays and medicants to kill off the fungous and bacterial enemies. His habit has been to check disease by weeding out and destroying the seedlings that showed sus- ceptibility to disease. The hardy individuals that remain owe their preservation to the fact that their tissues were able to fight off the inimical germs ; and it was ob- served that such immunity is a heritable trait, so that the individuals possessing it become the parents of an immune race. It might seem, then, that the method of the modern hygienist is a direct contravention of the method which the plant developer has found ad- vantageous. A strict application of Mr. Bur- [326] NURTURE VERSUS NATURE bank's method to the human plant would suggest that we lessen rather than increase the safe- guards against bacterial foes that surround the average child. The individual that is susceptible should, in this view, be permitted to succumb, in the interest of the race. Of course, no humanitarian can give assent to such a literal application of the knowledge of the plant breeder. Mr. Burbank himself would be the last to suggest such an application. We must recall that the aggregate conditions of civilization are artificial in the highest degree; that civilized man is and must everywhere remain a hothouse plant. The essential province of government is to give the weak protection against the strong, and against the adverse forces of nature. The manners and customs of civilized society have been built up in recognition of the fact that persons weak-bodied and susceptible to disease may have attributes of mind that make them among the most valuable members of society. Civilized man is not reared to compete with the denizens of the jungle, nor to submit to the hardships that may fall to the lot of barbaric tribes. His case is rather that of the tropical plant transported to temperate zones, which may require the constant protection of a hothouse environment, being quite unable to compete with plants of the field, yet being prized for the flow- ers that it puts forth, and regarded as fully worth the solicitous care necessarily bestowed upon it. Viewed in this light, the work of the euthenist [327] LUTHER BURBANK who seeks to better the environment of the race takes on a quite different aspect. The physical weakling that is saved from an early demise only by a pampering environment may prove an intel- lectual giant — a Newton, a Darwin, a Spencer — of greater benefit to the world than any conceivable number of physical giants. In a word, the fact that man is essentially an intellectual animal must be borne in mind at all stages of consideration of the problems of the eugenist. Yet the fact remains that the intellect of man is bound up with his physical organization; and it would be absurd to deny that the problem of the eugenist is primarily a physical one, even though it deals also with the mental organization. The ideal man must be sound of body as well as sound of mind; and the ultimate problem of the eugenist is, how to give us a race of human beings which shall combine in the fullest measure phys- ical vigor and mental vigor. ' t A sound mind in a sound body," was the familiar maxim of the ancient Greeks ; and it represents no less fully the ideal of the eugenist of to-day. If the work of the euthenist preserves a cer- tain number of weaklings who might perhaps, in a coldly critical view, be regarded as undesirables, it preserves also thousands of children who will grow into robust and vigorous adults. We have already suggested that even those who remained physical weaklings may have mental qualities that far outbalance their physical defects. Such phys- [328] NURTURE VERSUS NATURE ical weaklings with wonderful brains may have their strains blended with the strains of other individuals of robust physique, with the result of developing progeny showing an ideal blending of physical and mental qualities. So in the last analysis it appears that the work of the euthenist is in fullest harmony with that of the eugenist. Or, better stated, euthenics is but an aspect of the larger problems of eugenics. The ultimate ob- ject at which they both aim is the development of a race of human beings representing as close an approximation as may be to physical and mental perfection. And when we add that such ideal personali- ties command the instinctive admiration of man- kind in general (witness the universally ap- plauded heroes and heroines of stage and story), it requires no further argument to show that in their ultimate influence eugenics, euthenics, and normal love between the sexes are linked in a triumvirate at once harmonious and beneficent. THE END INDEX Acres, World's Most Productive, 178. Almonds, Hybrid, 220. Amaryllis, Bulbs of Hybrid, 193. Amateur, Suggestions for the, 74. Animal World, The, 301. Beans, Hybridizing, 114. Breeding, Complex Factors, 158. for Genius, 289. from the Unfit, 250. " of the Unfit, 310. " Selective Line, 33. Budding, The Process of, 67. Burbank, Early Experiments, 5. Methods and the Hu- man Plant, 18. " Methods in Outline, 245. Potato, 108. Burbank's Migration to Califor- nia, 6. Cactus, Spineless, 104. Calla, Making a Fragrant, 134. Characters, Accentuating De- sired, 165. " Fixing, 38. Chestnut, Dwarf, 208. " Trees, 207. Chicken vs. Egg, 267. Color, Studies in Variation, 162. Corn, Experiments with Sweet, 117. " Modern, and its Ancestry, 121. Crinum, Bulbs of Hybrid, 193. Crops, Rotation of, 187. Crossing, Selection without, 112. Dahlia, Studies in Color, 198. " Working with the Re- sponsive, 195. Darwin, 24. Degeneracy, Inbreeding for, 292. Elm Trees, 235. Environment and Heredity, 299. Eugenics, Positive, 321. The Principle of, 304. Eugenist, Nature as, 307. Euthenics, The Province of, 324. Flower, Ornamental Beds, 182. Flowers, Some Gigantic, 190. The Colors Explained, 36. Why They Have Per- fume, 133. Fruit, The Most Prolific Bearer, 103. Fruits, Creating New, 72. " Culture of Garden, 81. " New, for Orchard and Garden, 14. " Small, that Await De- velopment, 99. " Some New, 101. Galton's Law, Aid from, 254 Genius, Breeding for, 289. Germ-cell, Mechanism of the, 270. Germ-Plasm, Continuity of the, 264. " Modification of the, 265. " Mingling Modified, 275. Gladiolus, Improving the, 184. Grafting, Hurrying Seedlings by, 64. Grass, Substitutes for, 172. [331] INDEX Heredities, Remote, 168. Heredity and Environment, 299. Facts of, 272. " Mendelian, 31, 256, 281. Hints, Some Practical, 90. Hybrid Almonds, 220. Bulbs of Crinum and Amaryllis, 193. Peaches, 221. " Strange, Poppies, 146. Trees, 215. Walnuts, 217. Hybrids, Quantity Production, 85. Remarkable, 82. Hybridization and Variation, 277. Hybridizing Peas and Beans, 114. Possibilities, 223. Inbreeding for Degeneracy, 292. Insanity and Mendelism, 287. Lawn, Care of, 174. Leaf, Changing a, 138. Lilies, New, 144. Marriage, in Cousins, 258. Marriages, The Question of Re- stricting, 319. Mendel, Experiments, 115. Mendelian Heredity, 31, 256, 281. Mendelism and Insanity, 287. Monterey Pine, 295. Mutants, Production of, 279. Nature as Eugenist, 307. Nature's Game of Chance, 283. Old Methods, New Application of, 8. Orchards and Gardens, New Fruits for, 14. Paradox Walnut, 214. Parents, Selection of, 246. Pea, Making to Order a, 110. Peaches, Hybrid, 221. Peas, Hybridizing, 114. Pecan Nut, 224. Perfume in Flowers, 133. Pine, The Monterey, 295. Plant Breeding, New Knowledge from, 242. Plumcot, 73. Plums, 72. Pollenizing, Methods of, 154. Poppies, Strange Hybrid, 146. Poppy, New Colors in the, 136. Potato, Combining with To- mato, 122. " The Burbank, 108. Rhubarb, The Giant Winter, 297. Royal Walnut, 213. Seed, Planting the, 50. Seedlings, Care of the, 51. How to Select, 63. " Hurrying by Graft- ing, 64. Seeds and Seedlings, 59. " The Choice and Care, 46. Selection without Crossing, 112. Shrubs, Ornamental, 201. Soil, Preparing the, 48. Species, Constructing a New, 140. " Creating New, 57. " Quantity Production, 143. " The Origin of, 148. Thornless Blackberry, 95. Tomato, Combining with Po- tato, 122. Tree, Chestnut, 207. " Elm, 235. Trees, Development through Selection, 226. " Giants, 212. " Hybrid, 215. " Ornamental, 231. " Second-Generation, 217. " Walnut, 213. Unfit, Restricting the Fecun- dity, 313. " The Breeding of, 310. [332] INDEX Variation and 'Hybridization, Vines, Ornamental, 201. 277. Varieties, Production and Fix- Walnut, Paper Shell, 228. ing New, 151. " Paradox, 214. Seeking New, 70. " Royal, 213. " to Order, 87. " Trees, 213. Vegetables and Flowers, New, Water, Supplying, 180. 16. White, Blackberry, Making a, " Varied, 126. 93. [333] RETURN TO the circulation desk of any University of California Library or to the NORTHERN REGIONAL LIBRARY FACILITY Bldg. 400, Richmond Field Station University of California Richmond, CA 94804-4698 ALL BOOKS MAY BE RECALLED AFTER 7 DAYS 2-month loans may be renewed by calling (415)642-6753 1-year loans may be recharged by bringing books to NRLF Renewals and recharges may be made 4 days prior to due date DUE AS STAMPED BELOW JUL 1 6 1991 LD 21-100m-7,'33 YC i 08807 U.C. BERKELEY LIBRARIES