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Lrp. 1906 ~ All rights reserved LIBRARY of CONGRESS Two Copies Received APR 25 1906 CopyrieHT, 1895, 1906, By L. H. BAILEY. Set up and electrotyped. Published December, 1895. Reprinted April, 1896; August, October, 1897; March, r902; March, 1904. Fourth Edition, with additions, April, 1906. Norwood [ress J. S. Cushing & Co. — Berwick & Smith Co. Norwood, Mass., U.S.A. PREFACE. THERE is no subject associated with the care of plants respecting which there is so much mis- apprehension and imperfect knowledge, as that of the origination of new forms. Most of the scattered writing touching it treats the subject as if all our knowledge of the matter were and must be derived wholly from experiment. It therefore recites examples of how this and that new form has come to be, and has made little attempt to discover the fundamental causes of the genesis of the novelties. Horticulturists commonly look upon each novelty as an isolated fact, whilst we ought to regard each one as but an expression of some law of the variation of plants. It is the common notion, too, to con- sider any type of plant to: be essentially a fixed entity, and to regard any marked departure from the type as a phenomenon rather more to be Vv a . vi PREFACE. wondered at than to be explained. It is evident, however, that one cannot understand the pro- duction of new varieties until he has grasped some of the fundamental principles of the on- ward progression of the vegetable kingdom. Any attempt, therefore, to explain the origin of garden varieties, and the methoéls of producing them, must be at the same time a contribution to the literature of the philosophy of organic evolution. I do not know of any explieit and sustained attempt to account for the evolution of all gar- den forms, and I have therefore brought together in this volume the subject-matter of various lectures which I have been in the habit of giving before my students. The first and third lectures were newly elaborated the present summer for two addresses before the class in biology which came together at the University of Pennsylvania, under the auspices of the American Society for the Extension of Univer- sity Teaching. The second lecture was first presented before the Massachusetts State Board of Agriculture, in Boston, December 1, 1891. In April, 1892, it was republished, with a bibli- PREFACE. Vil ography of the subject, by the Rural Publishing Co., under the title, ‘‘ Cross-Breeding and Hybrid- izing.” This publication is now out of print. I have made no attempt to collect lists or cata- logues of varieties, but have endeavored to make very brief statements of some of the underlying principles of the amelioration of plants, with only sufficient examples to fix them in the mind. I hope that teachers of horticulture and botany may find the book useful in their classes. When it is necessary to abridge the instruction or to present it to untrained students, only Lectures III. and V. may be used, for these contain the matters of greatest demonstrative importance. i H. BAY, CoRNELL UNIVERSITY, IrHaca, N.Y., September 1, 1895. PREFACE TO THIRD EDITION. In the eight years since this book was sent to the printer, there have been great changes in our attitude toward most of the fundamental questions that are discussed in its pages. In fact, these years may be said to have marked a transition between two habits of thought in respect to the means of the evolution of plants, —from the points of view held by Darwin and the older writers to those arising from definite experimental studies in species and varieties. We have not given up the old nor wholly accepted the new, but it is ‘certain that our outlook is shifting. So far as practical plant-breeding is involved, the changing attitude is concerned chiefly with discussions of the nature of varieties and the nature of hybridi- zation. The chief practical result of the discussion of the nature of varieties is a re-defining of what a Viii PREFACE TO THIRD EDITION. 1x variety is, whereby we have come to recognize the fact, more clearly than heretofore, that not all differences in plants are of equal importance or significance. | The practical result of the discussions of hy- bridization is the growing belief that the offspring of hybridization follow definite laws. This state- ment seems to be wholly at issue with the tenor of Lecture II.; but the apparent contradictions are - largely such as follow from two sets of definitions of the ideas of “ variety” and “hybrid.” It must also be remembered that even if hybridization fol- lows definite laws, the practical results are com- monly so modified and obscured by interfering circumstances that safe predictions usually cannot be made. I had once thought of rewriting Lec- ture II., but on going over it again I found that the chief change that I should desire now to make would be a rephrasing in order to conform it to the method of current discussions. Moreover, we are not yet ready to make very positive discus- sions from the newer studies. The time cannot be far distant when the subject of plant-breeding will be rewritten from a new point of view. In the meantime, I hope that the new matter in x PREFACE TO THIRD EDITION. Lecture IV. may set the reader straight on some of the newer problems. The first issue of this book was made late in 1895. The second edition was made early in 1902. In the meantime it had been twice reprinted. By an inadvertence, the second edition was not so marked on the title-page. In that edition the changes in the text were few. The only very im- portant departure was the publication of a bibli- ography. This bibliography had appeared with my paper on “Cross-Breeding and Hybridizing,” which was published in 1892 as one of the Rural Library Series. It was purposely confined to such literature as English-speaking horticulturists _ would be most likely to find. The edition was soon exhausted, and many requests for this bibli- ography decided me to extend and republish it. In the present edition I have added somewhat to this bibliography (to the close of 1902), and have made some changes in the text; but the leading change is the substituting of new matter for the old Lecture IV. L. H. Barry CorNELL UNIVERSITY, Irnaca, N.Y., September 1, 1903. CONTENTS. LECTURE L Tue Fact anp PHILOSOPHY OF VARIATION. - . I. The Fact of Individuality . * ° ° ° The seed-individual. The bud-individual. Il. The Causes of Individual Differences ‘ : a. Fortuitous variation . : ° b. Sex as a factor in the variation of sini . c. Physical environment and variation . . 1. Variation in food supply . : . 2. Variation in climate . é : ° 3. Change of seed. Bud-variation ° d. Struggle for life a cause of variation . : Ill. The Choice and Fixation of Variations . ‘ LECTURE II. THE PHILOSOPHY OF THE CROSSING OF PLANTS, CONSID- ERED IN REFERENCE TO THEIR IMPROVEMENT UNDER CULTIVATION ¢ E A é é ; 4 ‘é I. The Struggle for Life . ° ° ° . Il. The Division of Labor ° . ° . . Ill. The Limits of Crossing - a ° ° ° xi ; 39 39 42 44 xii CONTENTS. IV. Function of the Cross : F . a. The gradual amelioration of the ee ‘ b. Change of seed and crossing : m c. The outright production of new varie ° V. Characteristics of Crosses . : : ° VI. Uncertainties of Pollination ° ° ° . Conclusion “ : . ° ° ° . LECTURE III. How DomEsTIC VARIETIES ORIGINATE 2 P ® 2 I. Indeterminate Varieties 5 . a RO ge Il. Plant-breeding . ; ‘ . “ : ; Rule 1. Antagonistic features . Rule 2. Quickest results in the most vane groups . : ; ; Rule 3. Breed for one thing a a fioab Rule 4. Contradictory attributes . Rule 5. Characters of the entire plant aie important . . Rule 6. Plants differ in haroeiaie power Rule 7. Less marked variations more impor- tant = Rule 8. Crossing a means, nit an ana Rule 9. Choice of parents toacross . Rule 10. The ideal should be mental Rule 11. Seek to produce variation in the desired direction . Rule 12. Watch for bud-varieties . Rule 13. Progress lies in selection . Rule 14. The type is kept up to standard by continued selection Rule 15. The best final results are to be os tained by high tillage and intelli- gent selection ; ; é ' CONTENTS. Xili Ill. Specific Examples. ase ° ° =. 429 The dewberry and blackberry ° ° Pe 1!) The apple a ° ° ° e F = Beans c . . . . : “tae gins 3) Cannas . . . , e ° . 140 LECTURE IV. RECENT OPINIONS; BEING A RESUME OF THE INVESTIGATIONS OF DE VRIES, MENDEL, AND OTHERS, AND A STATEMENT ——a OF THE CURRENT TENDENCIES OF AMERICAN PLANT- BREEDING PRACTICE . : : : ; : . 148 I. Some Recent Ideas on the Evolution of Plants . 144 a. Variation: De Vries . : : ‘ . 145 b. Heredity: Mendel . ; ‘ : . 155 _c. Application to Plant-breeding . ? Segre (i) d. Interpretation of Hybridism . . Seth e. Conclusion . eis : 2 : ety hID Mendelism in Wheat . = ; : «181 II. On Hybridization: De Vries. . : . 189 Ill. The Forward Movement in Plant-breeding - 202 LECTURE V. CuRRENT PLANT-BREEDING PRACTICE - * . « BRT I. Luther Burbank : . . Ss ths - 288 Il. squashes and pumpkins with which it will effect a _ cross, whether it is used as male or female parent. “ Even the imposing and ubiquitous great field pumpkin, which every New Englander associates with pies, is overpowered by the little gourd. Seeds from a large and sleek pumpkin which had been fertilized by gourd pollen, produced gourds and small hard-shelled globular fruits which were entirely inedible. A more interesting experiment was made between the handsome green-striped Ber- gen fall squash and the little pear gourd. Several flowers of the gourd were pollinated by the Bergen in 1889. The fruits raised from these seeds in 1890 were remarkably gourd-like. Some of these crosses were pollinated again in 1890 by the Ber- gen, and the seeds were sown in 1891. Here, then, were crosses into which the gourd had gone once and the Bergen twice, and both the parents are to all appearances equally fixed, the difference in strength, if any, attaching rather to the Bergen. POLLINATION IS UNCERTAIN. 83 Now, the crop of 1891 still carried pronounced characters of the gourd. Even in the fruits which most resembled the Bergen, the shells were almost flinty hard, and the flesh, even when thick and tender, was bitter. Some of the fruits looked so much like the Bergen that I was led to think that the gourd had largely disappeared. The very hard but thin paper-like shell which the gourd had laid over the thick yellow flesh of the Bergen, I thought might serve a useful purpose, and make the squash a better keeper. And I found that it was a great protection, for the squash could stand any amount of rough handling, and was even not injured by ten degrees of frost. All this was an acquisition, and, as the squash was handsome and exceedingly productive, nothing more seemed to be desired. But it still remained to have a squash for dinner. The cook complained of the hard shell, but, once inside, the flesh was thick and attractive, and it cooked nicely. But the flavor! Dregs of quinine, gall, and boneset! The gourd was still there ! VI. UNCERTAINTIES OF POLLINATION. We have now seen that uncertainty follows hybridization, and, in closing, I will say that uncertainty also attaches to the mere act of pollination. Between some species which are 84. PHILOSOPHY OF CROSSING PLANTS. closely allied and which have large and strong flowers, four-fifths of the attempts towards cross- pollination may be successful; but such a large proportion of successes is not common, and it may be infrequent even in pollinations between plants of the same species or variety. Some of , the failure is due in many cases to unskilful opera- tion, but even the most expert operators fail as often as they succeed in promiscuous pollinating. © There is good reason to believe, as Darwin has — shown, that the failure may be due to some selec-) tive power of individual plants, by which they re- fuse pollen which is, in many instances, acceptable to other plants even of the same variety or stock. The lesson to be drawn from these facts is that operations should be as many as possible, and that discouragement should not come from failure. In order to illustrate the varying fortunes of the pollinator, I will transcribe some notes from my field-book. Two hundred and thirty-four pollinations of gourds, pumpkins, and squashes, mostly between varieties of one species (Cucurbita Pepo), and in- cluding some individual pollinations, gave one hundred and seventeen failures and one hundred and seventeen successes. ‘These crosses were made in varying weather, from July 28 to August 30. In some periods nearly all the operations would succeed, and at other times most of them would were . _ ne ay RECORDS OF POLLINATIONS. 85 fail. I have always regarded these experiments as among my most successful ones, and yet but half of the pollinations “took.” But one must not understand that I actually secured seeds from even all these one hundred and seventeen fruits, for some of them turned out to be seedless, and some were destroyed by insects before they were ripe, or they were lost by accidental means. A few more than half of the successful pollinations — if by suc- cess we mean the formation and growth of fruit — really secured us seeds, or about one-fourth of the whole number of efforts. Twenty pollinations were made between potato flowers, and they all failed; also, seven pollinations of red peppers, four of husk-tomato, two of Nico- tiana affinis upon petunia and two of the reciprocal cross, twelve of radish, one of Mirabilis Jalapa upon M. longiflora and two of the reciprocal cross, three Convolvulus major upon C. minor and one of the reciprocal, one muskmelon by squash, two musk- melons by watermelon, and one muskmelon by cucumber. This is but one record. Let me give another: — Cucumber, ninety-five efforts: fifty-two suc- cesses, forty-three failures. Tomato, forty-three efforts: nineteen successes, twenty-four failures. Egeg-plant, seven efforts: one success, six failures. Pepper, fifteen efforts: one success, fourteen fail- ures. Husk-tomato, forty-five efforts: forty-five 86 PHILOSOPHY OF CROSSING PLANTS. failures. Pepino, twelve efforts: twelve failures. Petunia by Nicotiana affinis, eleven efforts: eleven failures. Nicotiana affinis by petunia, six efforts: six failures. General Grant tobacco by Nicotiana affinis, eleven efforts: eight successes, three fail- ures. Nicotiana affinis by General Grant tobacco, fifteen efforts: fifteen failures. General Grant tobacco by General Grant tobacco, one effort: one success. Nicotiana affinis by Nicotiana affinis, three efforts: two successes, one failure. ‘Tuberous be- gonia, five efforts: five successes. Total, three hundred and twelve efforts: eighty- nine successes, two hundred and twenty-three failures. CONCLUSION. And now, the sum of it all is this: encourage in every way crosses within the limits of the variety and in connection with change of stock, expecting increase in vigor and productiveness; hybridize if you wish to experiment, but do it carefully, systematically, thoroughly, and do not expect too much. Extend Darwin’s famous proposition to read: Nature abhors both perpetual self-fertiliza- tion and hybridization. LECTURE III. HOW DOMESTIC VARIETIES ORIGINATE. “THE key is man’s power of accumulative selection: nature gives successive variations ; man adds them up in certain directions useful to him.” ‘This, in Darwin’s phrase, is the essence of the cultivator’s skill in ameliorating the vege- table kingdom. So far as man is concerned, the origin of the initial variation is largely chance, but this start or variation once given, he has the power, in most cases, to perpetuate it and to modify its characters. There are, then, two very different factors or problems in the origination of garden varieties, — the production of the first de- parture or variation, and the subsequent breeding of it. Persons who give little thought to the sub- ject, look upon variation as the end of their endeav- ors, thinking that a form comes into being with all its characters well marked and fixed. In reality, however, variation is but the beginning ; selection is the end. I. INDETERMINATE VARIETIES. There are two general classes of garden varie- ties as respects the method of their origin, — 87 88 HOW DOMESTIC VARIETIES ORIGINATE. those which come into existence somewhat sud- denly and which require little else of the hus- bandman than the multiplication of them, and those which are the result of a slow evolution or direct breeding. The former are indeterminate or uncertain, and the latter are determinate or definite. The greater part of those in the first class are plants which are multiplied or divided by bud-propagation. They comprise nearly all our fruits, the woody ornamental plants, and such herbaceous genera as begonia, canna, gladiolus, lily, dahlia, carnation, chrysanthemum, and the like,— in fact, all those multiplied by grafting, cuttings, bulbs, or other asexual parts. The original plant may be either a seedling or a- bud- sport. The gardener, who is always on the look- out for novelties, discovers its good qualities and propagates it. Varieties which are habitually multiplied by buds, as in those plants which I have mentioned. in the last paragraph, vary widely when grown from seeds, so that every seedling may be markedly distinct. As soon, however, as varie- ties are widely and exclusively propagated by seeds, they develop a capability of carrying the greater part of the individual differences down to the offspring. That is, seedlings from bud- multiplied plants do not “come true,” as a rule, whilst those from seed-propagated plants do INDETERMINATE VARIETIES. 89 “come true.” The reason of this difference will become apparent upon a moment’s reflection. In the seed-propagated plants, like the kitchen-gar- den vegetables and the annual flowers, we select the seeds and thereby eliminate all those varia- tions which would have arisen had the discarded seeds been sown. In other words, we are con- stantly fixing the tendency to “come true,” for this feature of plants is as much a variation as form or color or any other attribute is. Suppose, for instance, that a certain variation were to re- ceive two opposite treatments, the seeds from one- half of the progeny being carefully selected year by year, and all those from untypical plants dis- carded, whilst in the other half all the seeds from all the plants, whether good or bad, are saved and sown. In the one case, it will be seen, we are fixing the tendency to “come true,” for this is all that constitutes a horticultural variety, — a brood which is very much like all its parents. In the other case, we are constantly eliminating the tendency to “come true” by allowing every modifying agency full sway. So the very act of taking seeds only from plants which have “ come true,” tends to still more strongly fix the heredi- tary force within narrow limits. Working against this restrictive force, however, are all the agencies of environment, so that, fortunately, now and then a seed gives a “rogue,” or a plant widely 90 HOW DOMESTIC VARIETIES ORIGINATE. unlike its parent, and this may be the start for a new variety. With bud-multiplied varieties, however, the case is very different. Here every seed may be sown, as in the illustrative case above, because the seedlings are not wanted for themselves, but simply as stocks upon which to bud or graft the desired varieties. So there is no seed selection in the ordinary propagation of apples, pears, peaches, . and the other orchard fruits. The seeds are taken indiscriminately from pomace or the refuse of can- ning and evaporating factories. But every annual<_ garden vegetable is always grown from seeds more or less carefully saved from plants which possess some desired attribute. There is no reason why the tree fruits should not reproduce themselves from seeds just as closely as the annual herbs do, if they were to be as carefully propagated by selected seeds through a long course of generations. There “ is excellent proof of this in the well-marked races or families of Russian apples. In that country, grafting has been little employed, and conse- quently it has been necessary to select seeds only from acceptable trees in order that the off- spring might be more acceptable. So the Russian apples have come to run in groups or families, each family bearing the mark of some strong ancestor. Most of the seedlings of the Duchess of Olden- burg are recognizable because of their likeness to, : 7 : : PLANT-BREEDING. 91 the parent. We may thus trace an incipient ten- dency in our own fruits towards racial characters. The Fameuse type of apples, for example, tends to perpetuate itself ; and a similar tendency is very well marked in the Damson and Green Gage plums, the Orange quince, Concord grape, and Hill’s Chili and Crawford peaches. But inas- much as bud-multiplication is so essential in nursery practice, we can hardly hope for the time when our trees and shrubs, or even our per- ennial herbs, will ‘“‘come true” with much cer- tainty. In them, therefore, we get new varieties by simply sowing the seeds; but in seed-propa- gated varieties we must depend either upon chance variations or else we must resort to definite plant- breeding. II. PLANT-BREEDING. The breeding of domestic animals is attended, for the most part, with such definite and often precise results that there has come to be a gen- eral desire to extend the same principles to plants. It is not unusual to hear well-informed people say that it is possible to breed plants with as much certainty and exactness as it is to breed animals. The fact is, however, that such exact- ness will never be possible, because plants are very unlike animals in organization, and because, 92. HOW DOMESTIC VARIETIES ORIGINATE. also, the objects sought in the two cases are char- acteristically unlike. Plants, as we have seen, are made up of a colony of potential individuals, and to breed between two plants by crossing means that we must choose the sex-parents from amongst as many individuals as there are flowers or branches on the two plants, whilst in animals we choose two definite personal parents. And these personal parents are either male or female, and the union is essential to the production of offspring, whilst in plants each parent —that is, each flower —is generally both male and female, and the union of two is not essential to the production of offspring, for the plant is capable of multiplying itself by buds. The element of chance, therefore, is one hundred, or more, to one in crossing plants as compared with crossing animals. Then, again, the plant-parents are modified profoundly by every environmental condition of soil and temperature and sunshine, or other external condition, since they possess no bodily temperature, no choice of conditions, and no volition to enable them to overcome the circumstances in which they are placed. Animals, on the contrary, have all these elements of personality, and the breeder is also able to control the conditions of their lives to a nicety. In view of all these facts, it is not strange that animals can be bred by crossing with more confidence than plants can. But there is another s censiamcl ANIMALS AND PLANTS. 93 and even more important difference between the breeding of animals and the breeding of plants. In animals, our sole object is to secure simply one animal or one brood of offspring. In plants, our object is, in general, to secure a race or genera- tions of offspring, which may be disseminated freely over the earth. In the bovine race, for example, our object in breeding is to produce one cow with given characters ; in turnips, our object is to produce a new variety, the seed of which will reproduce the variety, whether sown in Penn- sylvania or Ceylon. It is apparent, therefore, that any comparisons drawn between the breeding of animals and plants are likely to be fallacious. Is there, then, any such thing as plant-breeding, any possibility that the operator can proceed with some confidence that he may obtain the ideal which he has in mind? Yes, to a certain extent. It is apparent that the very first effort on the part of the plant-breeder must be to secure indi- vidual differences; for so long as the plants which he handles are very closely alike, so long there will be little hope of obtaining new varieties. He must, therefore, cause his plants to vary. In plants which are comparatively unvariable, it is frequently impossible to produce variations in the desired direction at once, but it is more important to “ break ” the type,— that is, to make it depart markedly from its normal behavior in any or 94 HOW DOMESTIC VARIETIES ORIGINATE. many directions (page 19). If the type once begins to vary, to break up into different forms, the operator may be sure that it will soon become plastic enough to allow of modification in the manner which he desires. But whilst it is im- portant or even necessary to break a well-marked type into many forms, it would no doubt be un- wise to encourage this tendency after it once appears, lest the plant acquire a too strong habit of scattering. ‘This initial variation is induced by changing the conditions in which the plant has habitually grown, as a change of seed, change of soil, tillage, varying the food supply, crossing. and the like. As a matter of fact, however, nearly all plants which have been long cultivated are already suf- ficiently variable to afford a starting-point for breeding. The operator should have a vivid mental picture of the variety which he designs to obtain ; then he should select that plant in his plantation which is the nearest his ideal, and sow the seeds of it. From the seedlings he should again select the individuals which most nearly approach his type, and so on, generation after generation, until the desired object is attained. It is important, if he is to make rapid progress, that he keep the same ideal in mind year by year, otherwise there will be vacillation and the prog- ress of one year may be undone by a counter ANTAGONISTIC FEATURES. 95 movement the following year. In this way, it will be found that almost any character of a plant may be either intensified or lessened. ‘This is man’s nearest approach to the Creator in his dominion over the physical forms of life, and it is great and potent in proportion as it sets for itself correct ideals in the beginning and adheres to them until the end. When beginning this selection or breeding for an ideal, it is important that impossible or contra- dictory results should be avoided. Some of the cautions and suggestions which need to be con- sidered are these : — 1. Avoid striving after features which are antag- onistic or foreign to the species or genus with which you are working. Every group of plants has be- come endowed with certain characters or lines of development, and the cultivator will secure quicker and surer results if he works along the same lines, rather than to attempt to thwart them. Nature gives the hint: let men follow it out, rather than to endeavor to create new types of characters. Let us take some of the solanaceous plants as examples. There are certain types of the genus solanum which have a natural habit of tuber-bearing, as the potato. Such species should be bred for tubers and not for fruits. There are _ other solanums, however, like the egg-plants and the pepinoes, which naturally vary or develop in 96 HOW DOMESTIC VARIETIES ORIGINATE. the direction of fruit-bearing, and these should be bred for fruits and not for tubers; and the same should be true in the related genera of tomatoes, red peppers, and physalis. Those ambitious per- sons who are always looking for a tuber-bearing tomato, therefore, might better concentrate their energies on the potato, for the tomato is not devel- oping in that direction; and even if the tomato could be made to produce tubers, it would thereby lessen its fruit production, for plants cannot main- tain two diverse and profitable crops at the same time. It is more reasonable, and certainly more_ practicable, to grow potatoes on potato plants and tomatoes on tomato plants. 2. The quickest and most marked results are to be expected in those groups or species which are nor- mally the most variable. There are a greater num- ber of variations or starting-points in such species ; but it also follows that the forms are less stable the more the species is variable. Yet the varia- tions, being very plastic, yield themselves readily to the wishes of the operator. Carriere puts the thought in this form: “The stability of forms, in any group of plants, is, in general, in inverse ratio to the number of the species which it contains, and also to the degree of its domestication.” The most variable types are the most dominant ones over the earth; that is, they occur in greater numbers and under more diverse conditions than / a VARIABLE TYPES. 97 the comparatively invariable types do. The com- posite, or sunflower-like plants, comprise a ninth or tenth of the total species of flowering plants, and the larger part of the subordinate types or genera contain many forms or species. Aster, goldenrod, the hawkweeds, thistles, and other groups, are representative of the cosmopolitan or variable types of composites. Whenever, for any reason, any type begins to decline in variability, it also begins to perish; it is then tending towards extinction. Monotypic genera—those which con- tain but a single species—are generally of local or disconnected distribution, and are, for the most part, vanishing remnants of a once dominant or important type. As a rule, most of our widely variable and staple cultivated species are mem- bers of large, or at least polytypic genera. Such, for example, are the apples and pears, peaches and plums, oranges and lemons, roses, bananas, chrysanthemums, pinks, cucurbits, beans, potato, grapes, barley, rice, cotton. A marked exception to this statement is maize, which is immensely variable and is generally held to have come from a single species; but the genesis of maize is un- known, and it is possible, though scarcely proba- ble, that more than one species is concerned in it. Wheat is also a partial exception, although the original specific type is not understood; and the latest monographers admit three or four other spe- H 98 HOW DOMESTIC VARIETIES ORIGINATE. cies to the genus, aside from wheat. There are other exceptions, but they are mostly unimportant, and, in the main, it may be said that the domi- nant domestic types of plants represent markedly polytypic genera. 3. Breed for one thing at a time. The person who strives at the same time for increase or modi- fication in prolificacy and flavor will be likely to fail in both. He should work for one object alone, simply giving sufficient attention to sub- sidiary objects to keep them up to normal stand- ard. This is really equivalent to saying that” there can be no such thing as the perfect all- around variety which so many people covet. Va- rieties must be adapted to specific uses, — one for shipping, one for canning, one for dessert, one for keeping qualities, and the like. The more good varieties there are of any species, the more widely and successfully that species can be cultivated. 4. Do not desire contradictory attributes in any variety. A variety, for example, which bears the maximum number of fruits or flowers cannot be expected to greatly increase the size of those organs without loss in numbers. This is well shown in the tomato. The original tomato pro- duced from six to ten fruits in a cluster, but as the fruits increased in size the numbers in each cluster fell to two or three. ‘That is, increase in size proceeded somewhat at the expense of numer- : SELECT FOR THE ENTIRE PLANT. 99 ical productivity; yet the total weight of fruit per plant has greatly increased. The same is true of apples and pears; for whilst these trees bear flowers in clusters, they generally bear their fruits singly. Originally, every flower normally set fruit. The reason why blackberries, currants, and grapes do not increase more markedly in size, is probably because the size of cluster has been given greater attention than the size of berry- Plants which now bear a full crop of tubers cannot be expected to increase greatly in fruit- bearing, as I have already explained under Rule 1. This fact is illustrated in the potato, in which, as tuber production has increased, seed production has decreased, so that potato growers now complain that potatoes do not produce bolls as freely as they did years ago. 5. When selecting seeds, remember that the char- acter of the whole plant is more important than the character of any one branch or part of the plant ; and the more uniform the plant in all its parts, the greater ts the likelihood that it will transmit its characters. If one is striving for larger flowers, for instance, he will secure better results if he choose seeds from plants which bear large flowers throughout, than he will if he choose them from some one large-flowering branch on a plant which bears indifferent flowers on the remaining branches, even though this given branch produce much larger L. OF C, 100 HOW DOMESTIC VARIETIES ORIGINATE. flowers than those borne on the large-flowered plant. Small potatoes from productive hills give a better product than large potatoes from unpro- ductive hills. The practice of selecting large ears from a bin of corn, or large melons from the grocer’s wagon, is much less efficient in produc- ing large products the following season than the practice of going into the fields and selecting the most uniformly large-fruited parents would be. A very poor plant may occasionally produce one or two very superior fruits, but the seeds are more likely to perpetuate the characters of the plant than of the fruits. The following experiences detailed by Henri L. de Vilmorin illustrate my proposition admirably: _ “T tried an experiment with seeds of Chrysanthe- mum carinatum gathered on double, single, and semi-double heads, all growing on one plant, and found no difference whatever in the propor- tion of single and double-flowered plants. In striped verbenas, an unequal distribution of the color is often noticed; some heads are pure white, some of a self color, and most are marked with colored stripes on white ground. I had seeds taken severally from all and tested alongside one another. ‘The result was the same. All the seeds from one plant, whatever the color of the flower that bore them, gave the same proportion of plain and variegated flowers.” UNIFORMNESS IN THE PARTS. 101 The second part of my proposition is equally as important as the first,—the fact that a plant which is uniform in all its branches or parts is more likely to transmit its general features than one which varies within itself. It is well known that bean plants often produce beans with various styles of markings on the same plant or even in the same pod, yet these variations rarely ever perpetuate themselves. The same remark may be appled to variations in peas. These illustra- tions only add emphasis to the fact that intending plant-breeders should give greater heed than they usually do to the entire plant, rather than confine their attention to the particular part or organ which they desire to improve. At first thought, it may look as if these facts are directly opposed to the proposition which I emphasized in my first lecture, that every branch of a plant is a potential autonomy, but it is really a confirmation of it. The variation itself shows that the branch is measurably independent, but it is not until the conditions or causes of the vari- ation are powerful enough to affect the entire plant that they are sufficiently impressed upon the organization of the plant to make their effects hereditary. There is an apparent exception to the law that the character of the entire plant is more impor- tant than any one organ or part of it, in the case 102 HOW DOMESTIC VARIETIES ORIGINATE. of the seeds themselves. That is, better results usually follow the sowing of large and heavy seeds than of small or unselected seeds from the same plant. This, however, does not affect the main proposition, for the seed is in a measure independent of the plant-body, and is not so directly influenced by environment as the other organs are. And, again, the seed receives a part of its elements from a second or male parent. The good results which follow the use of large seeds are, chiefly, greater uniformity of crop, increased vigor, often a gain in earliness and sometimes in bulk, and generally a greater ca- pacity for the production of seeds. These results are probably associated less with any innate he- reditable tendencies than with the mere vegeta- tive strength and uniformness of the large seeds. The large seeds usually germinate more quickly than the small ones, provided both are equally mature, and they push the plantlet on more vigorously. This initial gain, coming at the most critical time in the life of the new indi- vidual, is no doubt responsible for very much of the result which follows. The uniformity of crop is the most important advantage which comes of the use of large seeds, and this is obviously the result of the elimination of all seeds of varying degrees of maturity, of incomplete growth and formation, and of low vitality. PROGENY OF IMMATURE SEEDS 103 Another important consideration touching the selection of seeds is the fact that very immature seeds give a feeble but precocious progeny. ‘This has long been observed by gardeners, but Sturte- vant, Arthur, and Goff have recently made a critical examination of the subject. “It is not the slightly unripe seeds that give a noticeable increase in earliness,” according to Arthur, “ but very unripe seeds, gathered from fruit [tomatoes ] scarcely of full size and still very green. Such seeds do not weigh more than two-thirds as much as those fully ripe. They germinate readily, but the plantlets lack constitutional vigor and are more easily affected by retarding or harmful influences. If they can be brought through the early period of growth and become well estab- lished, and the foliage or fruit is not attacked by rots or blights, the grower will usually be re- warded by an earlier and more abundant crop of slightly smaller and less firm fruit. These char- acters will be more strongly emphasized in sub- sequent years by continuous seed propagation.” Goff remarks that the increase in earliness in tomatoes, following the use of markedly immature seeds, “is accompanied by a marked decrease in the vigor of the plant, and in the size, firmness, and keeping quality of the fruit.” These results are probably closely associated with the chemical constitution and content of the immature seeds. 104 HOW DOMESTIC VARIETIES ORIGINATE. The organic compounds have probably not yet reached a state of stability, and they therefore respond quickly to external stimuli when placed in conditions suitable to germination; and there is little food for the nourishment of the plantlet. The consequent weakness of the plantlet results in a loss of vegetative vigor, which is earliness (see Rule 11). Still another feature connected with the choice of seeds is the fact that in some plants, as in some Ipomceas, for example, the color of the seed is more or less intimately associated with the color of the flower which produced them and also with the color of the flowers which they will produce. 6. Plants which have any desired characteristics im common may differ widely in their ability to transmit these characters. It is generally impos- sible for the cultivator to determine, from the appearance of any given number of similar plants, which of them will give progeny the most unvari- able and the most like its parent; but it may be said that those individuals which grow in the most usual or normal environments are most likely to perpetuate themselves. A very unusual condi- tion, as of soil, moisture, or exposure, is not easily imitated when providing for the succeeding gen- eration, and a return to normal conditions of envi- ronment may be expected to be followed by a more or less complete return to normal attributes on the SELECT SEVERAL STARTING-POINTS. 105 part of the plant. If the same variation, there- fore, were to occur in plants growing under widely different conditions, the operator who wishes to preserve the new form should take particular care to select his seeds from those individuals which seem to have been least influenced by the imme- diate conditions in which they have grown. Again, if the same variation appears both in uncrossed and crossed plants, the best results should be expected in selecting seeds from the former. We have already seen, in the second lecture, how it is that crosses are unstable, and how the instability is apt to be the greater the _ more violent the cross. ‘ Cross-breeding greatly increases the chance of wide variation,” writes Henri L. de Vilmorin, “ but it makes the task of fixation more difficult.” It is very important, therefore, when selecting seeds from plants which seem to give promise of a new variety, to sow the seeds of each plant separately, and then make the subsequent selec- tions from’the most stable generation; and it is equally important that the operator should not trust to a single plant as a starting-point, when- ever he has several promising plants from which to choose. 7. The less marked the departure from the genius of the normal type, the greater, in general, is the likelihood that it will be perpetuated. ‘That 106 HOW DOMESTIC VARIETIES ORIGINATE, \ is, widely aberrant forms are generally unstable.\ This is admirably illustrated in crosses. The seed-progeny of crosses between closely related varieties, or between different plants of the same variety, is more uniform and generally more easy of improvement by selection than the progeny of hybrids. In uncrossed plants, the general ten- dency is to resemble their parents, and the greater the number of like ancestors, the greater is the ten- dency to “come true.” There is thought to be a tendency, though necessarily a weak one, to return to some particular ancestor, or to “date back.” This is known as atavism. The so-called atavistie forms are likely to be unstable, to break up into nu- merous forms, or to return more or less completely to the type of the main line of the ancestry. The following statements touching some of the rela- tions of atavism to the amelioration of plants, are the results of an excellent study of heredity in lupines by Louis Levéque de Vilmorin : — “1. The tendency to resemble its parents is generally the strongest tendency in any plant; “2. But it is notably impaired as it comes into conflict with the tendency to resemble the general line of its ancestry. “3. This latter tendency, or atavism, is con- stant, though not strong, and scarcely becomes impaired by the intervention of a series of gen- erations in which no reversion has taken place. CROSSING NOT AN END. 107 “4, The tendency to resemble a near pro- genitor (only two or three generations removed), on the other hand, is very soon obliterated if the given progenitor is different from the bulk of its ancestors.” 8. The crossing of plants should be looked upon as a means or starting-point, not as an end. We cross two flowers and sow the seeds. ‘The result- ing seedlings may be unlike either parent. Here, then, is variation. The operator should select that plant which most nearly satisfies his ideal, and then, by selection from its progeny and the progeny of succeeding generations, gradually ob- tain the plant which he desires. It is only in plants which are propagated by asexual parts—as grafts, cuttings, layers, bulbs, and the like—that hybrids or crosses are commonly immediately val- uable; for in these plants we really cut up and multiply the one individual plant which pleases us in the first batch of seedlings, rather than to take the offspring or seedlings of it. Thus, if any particular plant in a lot of seedlings of crosses of cannas, or plums, or hops, or strawberries, or ~ potatoes, is valuable, we multiply that one in- dividual. There is no occasion for fixing the variety. But any satisfactory plant in a lot of seed- lings of crosses of pumpkins, or wheat, or beans, must be made the parent of a new variety by sow- ing the seeds of it and then by selecting for seed- 108 HOW DOMESTIC VARIETIES ORIGINATE. parents, year by year, those plants which are best. “ The unsettled forms arising from crosses,” Focke f writes, “are the plastic material out of which | gardeners form their varieties.” , But even in the fruits, and other bud-propa- gated plants, crossing may often be used to as good advantage for the purpose of originating variation as it can in peas or buckwheat. It only requires a longer time to fix and select variations because the plants mature so slowly. Ordinarily, if the operator does not find satisfactory plants amongst the seedlings of any cross of fruit trees, he roots up the whole batch as profitless. But if he were to allow the best plants to stand and were to sow seeds from them, the second gen- eration might produce something more to his liking. But it is generally quicker to make another cross and to try the experiment over again, than to wait for unpromising seedlings to bear. This repeated repetition of the experiment, however, — continual crossing and sowing and uprooting, —is gambling. ‘Throwing dice to see what will turn up is a comparable proceeding. The sowing of uncrossed seed is little better. Peter M. Gideon sowed over a bushel of apple seed, and one seed produced the Wealthy apple.?\ 1The facts in the origination of the Wealthy apple, as re- lated to me by Mr. Gideon, are these: he first planted a bushel of apple seeds, and then each year, for nine years, he planted GUIDES TO CROSSING. 109 D. B. Wier raised a million seedlings of soft maple, and one plant of the lot had finely divided leaves, and is now Wier’s Cutleaved maple. Teas’ Weeping mulberry, which is now so deservedly popular, was, as Mr. Teas tells me, “merely an accidental seedling.” So this explains why the production of new varieties of fruits is always chance, whilst a skilled man can sit in his study in the winter time and picture to himself a new bean or muskmelon, and then go out in the next three or four summers and produce it. 9. If it is desired to employ crossing as a direct means of producing new varieties, each parent to the proposed cross should be selected in agreement with the rules already specified, and also because it pos- sesses in an emphatic degree one or more of the qualities which it is desired to combine; and the more uniformly and persistently the parent pre- sents a given character, the greater is the chance that it will transmit that character. It has already been said that crossing for the instant production of new varieties is most certain to give valuable enough seed to give a thousand trees. At the end of ten years, all the seedlings had perished (this was in Minnesota) except one hardy seedling crab. Then asmall lot of seeds of apples and crab apples was obtained in Maine, and from these the Wealthy came. There were only about fifty seeds in the batch of crab seed which gave the Wealthy; but before this variety was obtained, much over a bushel of seed had been sown, 110 HOW DOMESTIC VARIETIES ORIGINATE. results in those species which are propagated by buds, because the initial individual differences are not dissipated by seed-reproduction. This is especially true of hybridization, or crossing between distinct species ; for in such violent eross- ing as this the offspring is particularly likely to be unstable when propagated by seeds. ‘The re- sults of hybridization appear to be most certain in those plants which are grown under glass, and in which, therefore, the selection of the seed- parents is most carefully made, and where the conditions of existence are most uniform. The . most remarkable results in hybridization which have yet been attained are with the choicer glass- house plants, such as orchids, begonias, anthu- riums, and the hike. (Lecture II.) The more violent the cross, the less is the likeli- hood that desirable offspring will follow. Species which refuse to give satisfactory results when hybridized directly or between the pure stocks, may give good varieties when the “blood” has become somewhat attenuated through previous crossings. The best results in hybridizing our native grape with the European grape, for ex- ample, have come from the use of one parent which is already a hybrid. Two notable examples are the Brighton and Diamond grapes, raised by Jacob Moore. The Brighton is a cross of Con- cord (pure native) by Diana-Hamburg (hybrid of IMPORTANT HYBRIDS OF FRUITS. ji1 impure native and European). Diamond is a cross of Concord by Iona, the latter parent un- doubtedly of impure origin, containing a trace of the European vine. T. V. Munson’s Brilliant is a secondary hybrid, its parents, Lindley and Dela- ware, both containing hybrid blood. Others of his varieties have similar histories. Even when the cross is much attenuated —or three or four or even more times removed from a pure hybrid origin by means of subsequent crossings — it may still produce marked effects in a cross without introducing such contradictory characters as to jeopardize the value of the offspring. Amongst American fruit plants there are com- paratively few valuable hybrids. ‘The most con- spicuous ones are in the grapes, particularly the various Rogers varieties, such as Agawam, Lind- ley, Wilder, Barry, and others, which are hybrids of the European grape and a native species. Other hybrids are the Kieffer and allied pears (between the common pear and the Oriental pear), the Transcendent and a few other crabs (between the common apple and the Siberian crab), the Soulard and kindred crabs (between the common apple and the native Western crab), a few blackberries of the Wilson Early type (between the blackberry and the dewberry), the purple-cane raspberries (between the native red and black raspberries, and possibly sometimes 112 HOW DOMESTIC VARIETIES ORIGINATE. combined with the European raspberry), the Utah Hybrid cherry (between the Western sand cherry and the sand plum), and probably a few of the native plums. There is undoubtedly a fertile field for further work in hybridizing our fruits, particularly those of native origin, and also many of the ornamental plants; the danger is that persons are apt to expect too much from hybridization, and too little from the betterment of all the other conditions which so profoundly modify plants. Violent hybridizations generally give unsatisfactory and unreliable: results; but subsequent crossings, when the “blood” of the original species to the contract is considerably attenuated, may be expected to correct or over- come the first incompatibility, as explained above. 10. Establish the ideal of the desired variety firmly in the mind before any attempt is made at plant-breeding. If one is to make any progress in securing new varieties, he must first be an \> expert judge of the capabilities and merits of the plants with which he is dealing, otherwise | he may attempt the impossible or he may obtain — a variety which has no merit. It is important, | too, that the person bear in mind the fact that ~ a variety which is simply as good as any other in cultivation is not worth introducing. It should be better in some particular than any other in existence. The operator must know the PRODUCE AN INITIAL VARIATION. fa points of his plant, as an expert stock-breeder knows the. points of an animal, and he must possess the rare judgment to determine which characters are most likely to reappear in the offspring. Inasmuch as a person can be an ex- pert in only a few plants, it follows that he can- not expect satisfactory results in breeding any species which may chance to come before him. Persistent and uniform effort, continued over a series of years, is generally demanded for the production of really valuable varieties. Thus it often happens that one man excels all competitors in breeding a particular class of plants. The hor- ticulturist will recall, for instance, Lemoine in the breeding of gladiolus, Eckford in peas, Crozy in cannas, Bruant in pelargoniums, and others. There are now and then varieties which arise from no effort, but because of that very fact they reflect no credit upon the so-called originator, who is really only the lucky finder. So far as the originator is concerned, such varieties are merely chance. If, however, the operator — him- self an expert judge of the plant with which he deals — chooses his seeds with care and discrimi- nation, and then proposes, if need be, to follow up his work generation by generation by means of selection, the work becomes plant-breeding of the highest type. First of all, therefore, the operator must know I 114 HOW DOMESTIC VARIETIES ORIGINATE. what he can likely get, and what will likely be worth getting. Most persons, however, begin at the other end of the problem,— they get what they can, and then let the public judge if the effort has been worth the while. 11. Having obtained a specific and correct ideal, the operator must next seek to make his plant vary in the desired direction. This may be done by crossing, or by modifying the conditions under which the plant grows, as indicated in Lectures I. and II. If there are any two plants which possess indications of the desired attributes, cross them: amongst the seedlings there may be some which may serve as starting-points for further effort. A change in the circumstances or environment of the plant may start the desired attribute. If the plant must be dwarfer, plant it on poorer or drier soil, transfer it towards the poles, plant it late in the season, or transplant it repeatedly (see pages 25 and 143). Dwarf peas become climb- ing peas on rich, moist soils. If the plant must have large fruits, allow it more food and room, and give attention to pruning and thinning. Cer- tain geographical regions develop certain charac- ters in plants, as we have seen (page 24); if, therefore, the desired feature does not appear spontaneously or as a result of any other treat- ment, transfer the plant for a time to that region PRODUCE AN INITIAL VARIATION. 115 which is characterized by such attributes, if there is any such. The importance of growing the plant under conditions or environments in which the desired type of characters is most frequently found, is admirably emphasized in the evolution of varieties which are adapted to forcing under glass. Within a century,—and in many instances within a decade or two,—species which were practically unknown to glass-houses have produced varieties which are perfectly adapted to them. This has been accomplished by growing the most tractable existing varieties under glass, and then carefully and persistently selecting those which most com- pletely adapt themselves to their environment and to the ideals of the operator. One of the most remarkable examples of this kind is afforded by the carnation. In Europe it is chiefly a border or out-door plant, but within a generation it hag _ produced hosts of excellent forcing varieties in America, where it is grown almost exclusively as a glass-house flower. So the carnation types of Europe and America are widely unlike, and the unlikeness becomes more emphatic year by year because of the rapid aberrant evolution of the American forms. 3 : Sowing the seeds of hardy annual plants in the fall often generates a tendency to produce thick- ened roots. The plant, finding itself unable to 116 HOW DOMESTIC VARIETIES ORIGINATE. perfect seeds, stores its reserve in the root, and it therefore tends to become biennial. In this manner, with the aid of selection and the varia- tion of the soil, Carriere was able to produce good radishes from the wild slender-rooted charlock (Raphanus Raphanistrum). Lessened vigor, so long as the plant continues to be healthy, nearly always results in a compara- tive increase of fruits or reproductive organs. It is an old horticultural maxim that checking growth induces fruitfulness. It is largely in con= sequence of this fact that plants bear heaviest | when they attain approximate maturity. Trees are often thrown into bearing by girdling, heavy pruning, the attacks of borers, and various acci- dental injuries. ‘The gardener knows that if he keeps his plants in vigorous growth by con- stantly potting them on into larger pots, he will get little, or at least very late, bloom. The plant-breeder, therefore, may be able to induce the desired initial variation by attention to this principle. (See discussion of variation in rela- tion to food supply, page 16.) Arthur has re- { cently put the principle into this formula: “ A” decrease in nutrition during the period of growth of an organism, favors the development of the re- productive parts at the expense of the vegetative parts.” . A most important means of inducing variation > SIMULTANEITY OF VARIATION. Tit is the simple change of seed, the philosophical reasons for which are explained on pages 59 and 28. A plant becomes closely fitted or accus- tomed to one set of conditions, and when it is placed in new conditions, it at once makes an effort to adapt itself to them. ‘This adaptation is variation. No doubt the free interchange of » seeds between seed-merchants and customers is one of the most fertile causes of the enormous increase in varieties in recent times. When once a novel variety appears, others of a similar kind are likely soon to follow in other places, and some persons have supposed that there is a synchronistic variation in plants, or a tendency for lke variations to appear simultaneously in widely separated localities: There is perhaps some remote reason for this belief, because there is, as Darwin expresses it, an accumulative effect of domestication or cultivation, by virtue of which plants which long remain comparatively invariable may within a short time, when cultivation has been continued long enough, vary widely and in many directions; and it is to be expected that even when plants have long since responded to the wishes of the cultivator, an equal amount or accumulation of the force of domestication would tend to produce like effects in different places. But it is probable that by far the greater part of this synchronistic variation is simply an apparent 118 HOW DOMESTIC VARIETIES ORIGINATE. one, for whenever any marked novelty appears the attention of all interested persons is directed to looking for similar variations amongst their own plants. 12. The person who is wishing for new varieties should look eritically to all perennial plants, and particularly to trees and shrubs, for bud-varieties or sports. It has already been said (pages 28, 6) that the branches of a tree may vary amongst themselves in the same way in which seedlings vary, and for the same reasons. As a rule, any marked sport is capable of being perpetuated by bud-propagation. The number of bud-varieties now in cultivation is really very large. Many of the cut-leaved and colored or variegated varieties of ornamental plants were originally found upon other trees as sports. The “ mixing in the hill” of potatoes is bud-variation. Nectarines are derived from the peach, some of them as sports and some as seedlings. ‘The moss-rose was prob- ably originally a sport from the Provence rose. Greening apple trees often bear russet apples, and russet trees sometimes bear greenings. So far as I know, there are no varieties of annual plants which have originated as sports. The probable reason for this is the fact that the duration of the plant is short and that its constitution is not pro- foundly modified in a single generation by the new circumstances in which it is placed every BUD-VARIETIES. 119 year. The effects of the conditions in which it lives are recorded in the seeds, and the plant dies without allowing a second season of growth to express the impressions which were received in a former generation. The fact that every branch of an annual plant—as of perennials —is unlike every other branch, is evidence enough that the annual is not unlike the perennial in fundamental constitution ; and there is every reason to believe that if any given annual were to become a peren- nial, it would now and then develop differences sufficiently pronounced to make them worthy the name of sports, the same as hyacinths, bouvardias, trees, and all other perennial plants are apt to do. Bud-varieties may not only come true from buds —as grafts, cuttings and layers, —but they occa- sionally perpetuate themselves by seeds. Now, these seedlings are amenable to selection, just the same as any other seedlings are; the bud-variety, therefore, may give the initial starting-point for plant-breeding. But, more than this, it is some- times possible to improve and fix the type by bud-selection as well as by seed-selection. Dar- win cites this interesting testimony: “ Mr. Salter brings the principle of selection to bear on varie- gated plants propagated by buds, and has thus greatly improved and fixed several varieties. He informs me that at first a branch often produces variegated leaves on one side alone, and that the 120 HOW DOMESTIC VARIETIES ORIGINATE. leaves are marked only with an irregular edging, or with a few lines of white and yellow. To im- prove and fix such varieties, he finds it necessary to encourage the buds at the bases of the most distinctly marked leaves and to propagate from them alone. By following, with perseverance, this plan during three or four successive seasons a dis- tinct and fixed variety can generally be secured.” Ernest Walker, a careful gardener at New Albany, Indiana, is of the opinion that the abnormal char- acter of sports often intensifies itself if the sport is allowed to remain upon the parent plant for a considerable time. He has observed this particu- larly in coleus, where color sports are frequent. “In these,” he says, “the sport begins with a branch, which may be taken off and propagated as anew variety. If left on the parent, other parts of the plant are apt to show similar variations. Indeed, I think it is not best to be in too great a hurry to remove a sporting branch, for its char- acter seems to tend to become more fixed if it remains on the plant.” 13. The starting-point once given, all permanent progress lies in continued selection. ‘This, as I have already pointed out, is really the key to the whole matter. In the greater number of cases, the oper- ator cannot produce the initial variation which he desires, but, by looking carefully amongst many plants, he may find one which shows an indication SELECTION THE KEY-NOTE. 121 of his ideal. This plant must be carefully saved, and all the seeds sown in a place where crossing with other types cannot take place. Of a hun- dred seedlings from this plant, mayhap one or two will still further emphasize the character which is sought. These, again, are saved and all the seeds are sown. So the operation goes on, patiently and persistently, and there is reward at the end. ‘This is the one eternal and funda- mental principle which underlies the amelioration of plants under the touch of man; and because we know, from experience, that it is so important, we are sure, as Darwin was, that selection in nature must be the most potent factor in the progress of the vegetable world. But suppose this suggestion of the new variety does not appear amongst the batch of plants which we raise? Then sow again; vary the con- ditions; select the most widely variable types; cross; at length —if the ideal is true —the sug- gestion will come. “Cultivation, diversification of the conditions of existence, and repeated sow- ings” are the means which Verlot would employ to induce variations. But the skill and the char- acter of the final result lie not so much in the securing of the initial start, as in the subsequent selection. Nature affords starting-points in end- less number, but there are few men alert and skil- ful enough to take the hint and improve it. If I 122 HOW DOMESTIC VARIETIES ORIGINATE. | want a new tomato, I first endeavor to discover what I want. I decide that I must have one like the Acme in color, but more spherical, with a firmer flesh, and a little earlier. Then I shall raise an acre of Acme tomatoes, and closely allied varieties ; or if I cannot do that, I make arrange- ments to inspect my neighbor’s fields. I seruti- nize every plant as the first fruits are ripening. Finally, I find one plant —not one fruit — which is something hke the variety which I desire. Very well! Wait two to five years, and you shall see my new variety ! Some of these initial variations possess no ten- dency to reproduce themselves. The seedlings of them may break up into a great diversity of forms, no form representing the parent closely. In such cases, it is generally useless to proceed further with this brood. Another start should be made with another plant. So it is always impor- tant, as we have already seen (Rule 6), to have as many starting-points as possible, to lessen the risk of failure. Whilst it requires nice judgment to se- lect those plants which possess the most important and the most transmissible combination of charac- ters, the greatest skill is nevertheless required to carry forward a correct system of selection. 14. Kven when the desired variety is obtained, it must be kept up to the standard by constant attention to selection. ‘That is, there is no real stability in SELECTION TO MAINTAIN PURITY. 123 the forms of plant life. So long as the conditions of existence vary, so long will plants make the effort to adapt themselves to the changes. No two seasons are alike, and no two fields, or even parts of fields, are alike; and there are no two cultivators who give exactly the same and equal attention to tillage, fertilizing, and the other treatments of plants. All forms or varieties, therefore, tend to “run out” by variation or gradual evolution into other forms; but because we keep the same name for all the succeeding generations, we fancy that we still have the same variety. In 1887 I found a single tomato plant in my garden in Michigan, which had several points of superiority over any other of the one hundred and seventy varieties which I was then growing. It came from a packet of German seed of an inferior variety. The tomato was very solid, an unusually long keeper, productive, and attractive in size and appearance. The variation was so promising that I named it in a sketch of tomatoes which I published that year, calling it the Ignotum (that is, wnknown), to indicate that the origin of it was no merit of my own. I sent seeds to a few friends for testing. I sowed the seeds for about five hundred plants in 1888 in an isolated patch upon uniform soil. The larger part of the plants were more or less like the parent. A few reverted. A few of the best 124 HOW DOMESTIC VARIETIES ORIGINATE. plants were selected, and the seed saved. I then moved to New York and took the seed with me. This was sown in uniform soil in an iso- lated position in 1889. This crop, probably as a result of the careful selection of the year before and of the change of locality, was remarkably uniform and handsome. Of the 442 plants which I grew that year, none reverted to the little Eiformige Dauer, the German variety from which it had come, but there was some variation in them due to different methods of treatment. I again saved the seeds, and I was now ready to intro- duce the variety. I therefore sold my seed, six pounds, to V. H. Hallock & Son, Queens, New York, who introduced it in 1890. The very next year, 1891, I obtained the Ignotum from fifteen dealers and grew the plants side by side. Of the fifteen lots, eight bore small and poor fruits which were not worth growing and which could not be rec- ognized as Ignotum! Grown from our own seed, it still held its characters well. Here, then, only a year after its introduction, half the seedsmen were selling a spurious stock. It is possible that some of this variation arose from substitution of other varieties by seedsmen, although I have yet secured no evidence of any unfair dealing. It is possible, also, that the product of some of the samples which I early sent out for testing had found their way into seedsmen’s hands. But I am DURATION OF VARIETIES. 125 convinced that very much of this variation was a legitimate result of the various conditions in which the crops of 1890 had been grown, and the varying ideals of those who saved the seeds. I am the more positive of this from the fact that the Ignotum tomato, as I first knew it and bred it, appears to be lost to cultivation, although the name is still used for the legitimate family of descendants from my original stock. All this experience illustrates how quickly varieties pass out -by variation and by the unconscious and unlike selection practised by different persons. The duration of any variety is inversely propor- tional to the frequency of its generations. Annual plants, other conditions being the same, run out sooner than perennials, because seed-reproduc- tion—or the generations—intervenes more fre- quently. Trees, on the other hand, carry their variations longer, because the seed-generations — -in which departures chiefly take place —are far- ther apart. Of all the so-called fruit plants, the strawberry runs out soonest and the varieties change the oftenest, because a new generation can be brought into fruit-bearing in two years, whilst it may require a decade or more to bring a new generation of apples or chestnuts into bearing. Yet, my reader will remind me that the Wilson strawberry has been and is the leading variety in many places for nearly forty years, to which I 126 HOW DOMESTIC VARIETIES ORIGINATE. reply that the Wilson of to-day is not necessarily the same as that introduced by James Wilson, simply because the name is the same. Every dif- ferent soil or treatment tends to produce a different strain or variation in the Wilson strawberry, as it does in any other plant ; and every grower, when setting a new plantation, selects his plants from that part of his field which pleases him best, rather than from those plants which most nearly correspond to the original type of the Wilson. That is, this unconscious selection on the part of the grower takes no account of what the variety was, but only of what it ought to be, and this ideal differs with every person. It is not surpris- ing, therefore, to find strains of Wilson strawberry which are as unlike as many named varieties are ; and it is to be expected that all of the strains now in existence have departed considerably from the original type. This example borrowed from the strawberry is a most important one, because it illustrates how a variety may vary and pass out of existence even though it is propagated wholly asexually, or by buds. There are to-day several different types of Rhode Island Greening apple in cultivation, which have originated from variations produced by envi- ronment and by the different models which propa- gators have had in mind; and the same is true of many other fruits. AMELIORATION DUE TO SELECTION. 12T All the foregoing remarks demonstrate the importance of constant attention to selection if one desires to maintain the exact type of any variety which he has produced. They explain the value of the “‘roguing”—or systematic de- struction of all “rogues” or non-typical plants — which is invariably practised by all good seed- growers. But they still more emphatically show that every variety is essentially unstable, and that the only abiding result is constant evolution, the old forms being left behind as the type expands into new and better strains. Varieties to be valu- able, therefore, ought not to be rigidly fixed, and, fortunately, nature has prescribed that they can- not be. Probably every decade sees a complete change in every variety of any annual species which is propagated exclusively from seeds, and every century must see a like change in the tree fruits. These changes are so gradual, and the original basis of comparison fades away so com- pletely, that we generally fail to recognize the evolution. 15. It is evident, therefore, that the most abiding progress in the amelioration of plants must come as a result of the very best cultivation and the most intel- ligent selection and change of seed. Every reflec- tive person must admit that the cultivation of plants — which is the fundamental conception of agriculture — has been and is crude and imperfect, 128 HOW DOMESTIC VARIETIES ORIGINATE. and that there has been no conscious effort on the part of the human race to produce any given final re- sult upon the cultivated flora. Yet, this imperfect cultivation has already modified plants so pro- foundly that we cannot determine the originals of many of them, and we can trace the evolution of but few. The science of rural industry is now fairly well understood in its essential fundamental | principles, and the intelligence of those classes of | persons who deal with plants is rapidly enlarging. | The opening of the twentieth century will virtu- ally mark a new era for agriculture, and from that time on the onward evolution of plants should proceed confidently and unchecked. Our eyes are too often dazzled by the novelties which suddenly thrust themselves upon us, and we look for some | mystic power which shall enable us to produce varieties forthwith at our will. We need not so much varieties with new names as we do a general increase in productiveness and efficiency of the types which we already possess ; and this augmen- tation must come chiefly in the form of a gradual evolution under the stimulus of good care. The man who will accomplish most for the amelioration and unfolding of the forms of plants, is he who fixes his eyes steadily upon the future, and with the inspiration of a long forecast, urges the better- ment of all conditions in which plants grow. DEWBERRY AND BLACKBERRY. 129 III. Sprecitric EXAMPLES. The foregoing principles and discussions will become more concrete if a few actual examples of the origination of varieties are given. In order to begin with a very simple case, I will relate the introduction of the varieties of dewberries, for this fruit is yet little cultivated, the varieties are few, and the domestication of it is not yet thirty years old. The Dewberry and Blackberry. The dewberries are native fruits, and it is only within the last ten years that they have become prominent among fruit-growers. ‘The most impor- tant one is the Lucretia. This was found grow- ing wild upon a plantation in West Virginia in war time. In 1876, a few of the plants were sent to Ohio, and from this start the present stock has come. It is probable that similar wild varieties are growing to-day in many parts of the country, but they have not chanced to have been seen by per- sons who are interested in cultivating them. It is a form of the common wild dewberry, which grows all over the northeastern states. Just why this particular patch in West Virginia should have been so much better than the general run of the species, nobody knows, but it was undoubtedly the prod- uct of some local environment of soil or position. : | 130 HOW DOMESTIC VARIETIES ORIGINATE. Early in the seventies, IT’. C. Bartel, of Huey, Clinton Co., Illinois, observed very excellent dew- berries growing in rows between the lines of stubble in an old cornfield, where the plant had evidently been quick to avail itself of unoccupied land. This was introduced as the Bartel dew- berry, and is now the second in point of promi- nence amongst the cultivated varieties. Other varieties have appeared in much the same way. A fruit-grower in Michigan found an extra good dewberry in a neighboring wood-lot, and intro- duced it under the name of Geer, in compliment to the owner of the place. In Florida, an un- usually good plant of the common wild dewberry of that region was discovered, and introduced by Reasoner Brothers, under the name of Manatee. There are now about twenty named varieties of dewberries in cultivation, as described in our horticultural writings, all of which, so far as I know, are chance plants from the wild. As the dewberries become more widely grown, good seedlings will now and then appear in cul- tivated ground, and these will be named and sold. After a time persons will begin to sow seeds for the purpose of producing new varieties ; and those seedlings which chance to possess un- usual merit will be propagated, and in due time introduced. ‘This is the history of the cultivated blackberries and raspberries which have come EVOLUTION OF THE APPLE 131 from the wild plants in less than half a century. These fruits are now so far developed that we no longer think of looking to the woods and copses for new varieties of promise, but the novelties are mostly chance seedlings from cultivated varieties. A few years ago a friend purchased plants of the Snyder blackberry. When they came into bear- ing he noticed that one plant was better than the rest. It bore larger fruits, and the bearing season was longer. He took suckers from this plant, and from these others were taken, until he now has a large plantation of the novelty, mostly selected from plants which pleased him best. The variety has such distinct merit that I have named it the Mersereau, in honor of the man who recognized and propagated it. He will continue selecting from the best plants, as he propagates year by year, and it may be that in a few years he will have so much improved it that it will no longer be the variety with which he started. The Apple. The original apple is not definitely known, but it was certainly a very small and inferior, crabbed fruit, borne mostly in clusters. When we first find it described by historians, it was still of small value. Pliny said that some kinds were so sour as to take the edge off a knife. But better and 132 HOW DOMESTIC VARIETIES ORIGINATE. better seedlings continued to come up about habi- tations, until, when printed descriptions of fruits began to be made, three or four hundred years ago, there were many named kinds in existence. The size had vastly improved, and with this in- crease came the reduction of the number of fruits in the cluster; so that, at the present time, whilst apple flowers are borne in clusters, the fruits are generally borne singly. That is, most of the flowers fail to set fruit, and they complete their mission when they have shed their pollen for the benefit of the one which persists. The American colonists brought with them the staple varieties of the mother countries. But the needs of the new country were unlike those of the old, and the tastes and fashions of the people were changing. So, as seedlings came up about the buildings and along the fences, where the seeds had been scattered, the ones which prom- ised to satisfy the new needs best were saved, and many of the old varieties were allowed to pass away. In 1817, the date of the first American fruit-book, over sixty per cent of the varieties particularly recommended for cultivation in this country were of American origin. In 1846, nearly two hundred varieties of apples were de- scribed as having been fruited in this country, of which over half were of American origin. Be- tween these two dates, introductions of foreign EVOLUTION OF THE APPLE. 133 varieties had been freely made, so that the per- centage of domestic varieties had fallen. But the next thirty years saw a great change. Of 1823 varieties described in 1872, nearly or quite seventy per cent were American, and a still greater proportion of the most prized kinds were of domestic origin. In the older states, the apple had now become so thoroughly accustomed to its environment, and the tastes of the people were so well supplied, that there was no longer much need for the introduction of foreign kinds. It was not so in the Northwest. There the apples of the eastern states did not thrive. The climate was too cold and too dry. Attention was turned to other countries with similar or rigorous cli- mate. In 1870, the Department of Agriculture at Washington imported cions of many varieties of apples from Russia; but these did not satisfy many fruit-growers of the northern states. It was then conceived that the great interior plain of Russia should yield apples adapted to the upper Mississippi valley, whilst those already imported had come from the seaboard territory. Accord- ingly, early in the eighties, Charles Gibb, of the province of Quebec, and Professor Budd, of Iowa, went to Russia to introduce the promising fruits of the central plain. The result has been a most interesting one to the pacific looker-on. There are ardent advocates of the Russian varieties, and 134 HOW DOMESTIC VARIETIES ORIGINATE. there are others who see nothing good in them. There are those who believe that all progress must come by securing seedlings from the hardi- est varieties of the eastern states; there are others who would derive everything from the Siberian crabs, and still others who believe that the final result lies in improving the native crabs. There is no end of discussion and cross-purposes. In the meantime, nature is quietly doing the work. Here is a good seedling of some old variety, there a good one from some Russian, and now and then one from the crab stocks. The new varieties are gradually supplanting the old, so quietly that few people are aware of it; and by the time the con- testants are done disputing, it will be found that there are no Russians and no eastern apples, but a brood of northwestern apples which have grown out of the old confusion. All these new apples are simply seedlings, almost all of them chance trees which come up here and there wherever man has allowed nature a bit of ground upon which to make garden as she likes. In 1892, there were 878 varieties of apples offered for sale by American nurserymen, and it is doubtful if one in the whole lot was the result of any attempt on the part of the originator to produce a variety with definite qualities. And what is true of the apple, is about equally true of the other tree fruits. In the small fruits and BEANS. 135 the grapes, where the generations are shorter and the results quicker, more has been done in the way of direct selection of seeds and the crossing of chosen parents; but even here, the methods are mostly haphazard. Beans. Perhaps there are no plants more tractable in the hands of the plant-breeder than the garden beans. Some two or three years ago, a leading eastern seedsman conceived of a new form of bean pod which would at once commend itself to his customers. He was so well convinced of the merits of this prospective variety, that he made a descriptive and “taking” name for it. He then wrote to a noted bean-raiser, describing the pro- posed variety and giving the name. “Can you make it for me?” he asked. ‘“ Yes, I will make you the bean,” replied the grower. ‘The seeds- man then announced in his catalogue that he would soon introduce a new bean, and, in order to hold the name, he published it, along with the announcement. ‘Two years later, I visited the bean-grower. ‘ Did you get the bean?” I asked. “Yes, here it is.” Sure enough, he had it, and it answered the requirements very well. Another seedsman would like a round-podded, stringless, green-podded bean. This same man _ produced 136 HOW DOMESTIC VARIETIES ORIGINATE. it, and I went into a field of fifteen acres of it, where it was growing for seed, and the most fas- tidious person could not have asked for a closer approach to the ideal which the breeder had set before him some four or five years before. How is all this done? It looks simple enough. The ideal is established first of all. The breeder revolves it in his mind, and eliminates all the impracticable and contradictory elements of it. Then he goes carefully and critically through his bean fields, particularly those varieties which are most like the desired kind, and marks those plants which most nearly approach his ideal ‘The seeds of these are carefully saved, and they are planted in isolated positions. If he finds no promising variations amongst his plantations, then he must start off the variation in some other way. This is usually done by crossing those varieties which are most lke the proposed kind. He has got a start ; but now the science and skill begin. Year by year he selects just those plants which please him best and which he judges, from experience, will most surely carry their features over to the offspring. He starts with one plant; the next year he may have only two. If he has ten or twenty good ones, then the task is an easy one, for the variety has elements of permanence — that is, of hereditability —in it. But he may have no plants the second year. In that case, he begins BEANS. 137 again; for if the ideal is true, it can be attained. This bean-breeder to whom I have referred, and upon whom many of our best seedsmen rely for new varieties, tells me that he has discarded fully three thousand varieties and forms as profitless. This only means that he is a most astute judge of beans, and that he knows when any type is likely to prove to be a poor breeder. The bean also affords an excellent example of the care which it is generally necessary to exercise to keep any variety true to the type. The person of whom I have spoken, in common with all care- ful seed-growers, searches his field with great pains to discover the “rogues,” or those plants which vary perceptibly from the type of the given variety. ‘The rogue may be a variation in size or habit of plant, season of maturity, color or form of pods, productiveness, susceptibility to rust, or other aberrance. In the dwarf or bush beans, which are now most exclusively grown, the most frequent rogue is a climbing or half-climbing plant. This is a reversion to the ancestral type of the bean, which was no doubt a twining plant. This rogue is always destroyed, even though it may be, itself, a good bean. In some cases, the men who perform the roguing are sent along every row of a whole field on their hands and knees, critically examining every plant. The ef- fect of this continual selection is always to push 488 HOW DOMESTIC VARIETIES ORIGINATE. on the variety to greater excellence. The vari- ous “improved” strains of plants are obtained in essentially this fashion. If the grower has been | painstaking with his roguing, he soon finds that his seed gives better and more uniform crops than the common stock of the variety. If the improve- ment is marked, he may dignify his strain with a distinct name, and it thereby becomes a new variety. The improvement may be a very im- portant one to a careful bean-grower, and at the same time be so slight as to escape the attention of the general farmer, or even of experimenters who are not particularly skilled in judging the merits of beans. All these examples drawn from the bean are excellent illustrations of the best and most scien- tific plant-breeding, and the same methods — varied to suit the different needs — apply to the ameliora- tion of all other plants. The recent dwarf Lima beans may be cited as examples of accidental or fortuitous varieties, in which the preconstructed~ ideal of the plant-breeder had no place. Four or ~ five of these beans have attained some prominence. Henderson and Kumerle dwarf Limas were intro- duced in 1889, Burpee in 1890, and Barteldes in 1892 or 1893. The variety which is now called the Henderson was picked up twenty or more years ago by a negro, who found it growing along a roadside in Virginia. It was afterwards grown BEANS. 139 in various gardens, and about 1885 it fell into the hands of a seedsman in Richmond. Henderson purchased the stock of it in 1887, grew it in 1888, and offered it to the general public in 1889. The introduction of Henderson’s bean attracted the attention of Asa Palmer, of Kennett Square, Pennsylvania, who had also been growing a dwarf Lima. He called upon Burpee, the well-known seedsman of Philadelphia, described his variety, and left four beans for trial. These were planted in the test grounds and were found to be valuable. Mr. Palmer’s entire stock was then purchased, — comprising over an acre, which had been carefully. inspected during the season—and Burpee Bush Lima was presented to the public in the spring of 1890. Mr. Palmer’s dwarf Lima originated in 1883, when his entire crop of Large White (Pole) Limas was destroyed by cut-worms. He went over his field to remove the poles before fitting the land for other uses, but he found one little plant, about ten inches high, which had been cut off about an inch above the ground but which had re-rooted. It bore three pods, each containing one seed. These three seeds were planted in 1884, and two of the plants were dwarf, like the parent. By discarding all plants which had: a tendency to climb, in succeeding crops, the Burpee Bush Lima, as we now have it, was developed. The Kumerle, Thorburn, or Dreer, Dwarf Lima originated from 140 HOW DOMESTIC VARIETIES ORIGINATE. occasional dwarf forms of the Challenger Pole Lima, which J. W. Kumerle, of Newark, New Jersey, found growing in his field. The stock which came from these selected dwarf plants was introduced by Thorburn and Dreer, under their respective names. The singular Barteldes Bush Lima came from Colorado, and is a similar dwarf sport of the old White Spanish or Dutch Runner bean. Barteldes received about a peck of the seed and introduced it sparingly. It attracted very little attention, and as the following season was dry, Barteldes himself failed to get a crop, and the variety was lost to the trade. Cannas. Few plants have shown more remarkable evolu- tions in very recent years than the cannas. At the present time, the Crozy cannas—so named from Crozy, of Lyons, France, who has introduced the greater number of them —are most popular. This type is often called the French Dwarf, or the Flowering Canna, and it is marked by a com- paratively low stature, and very large and showy spreading flowers in many colors, whereas the can- nas of a few years ago were very tall plants, with small and late dull red, narrow flowers, and they were grown exclusively for their foliage effects. How has this transformation come about? CANNAS. 141 In the first place, it should be said that there are many species of canna, and about a half dozen of these were well known to gardeners at the opening of the century. About 1830, the cannas began to attract much attention from cultivators, and the original species were soon variously hybrid- ized. Crossed seeds, and seeds from the succes- sive generations of hybrids, introduced a host of new and variable forms. ‘The first distinct fash- ion in cannas seems to have been for tall, late- flowering forms. In 1848, Année, a cultivator in France, sowed seeds of Canna Nepalensis, a tall oriental species, and there sprung up a race of plants which has since been known as Canna Annei. It is probable that this Canna Nepalensis had become fertilized with other species growing in Année’s collection, very likely with Canna glauca. At any rate, this race of cannas became popular, and was to its time what the French dwarfs are to the present day. The plants were freely introduced into parks, beginning about 1856, but their use began to wane by 1870 or before. Descendants of this type, variously crossed and modified, are now frequently seen in parks and gardens. The beginning of the modern race of dwarf; large-flowered cannas was in 1863, when one of the smaller-flowered Costa Rican species (Canna Warscewiczil) was crossed upon a large-flowered 142 HOW DOMESTIC VARIETIES ORIGINATE. Peruvian species (Canna iridiflora). The off- spring of this union came to be called Canna Ehemanni. This hybrid has been again variously crossed with other species, and modified by culti- vation and selection, until the present composite type is the result. Seeds give new varieties; and any seedling which is worth saving is thereafter multiplied by divisions of the root, and the result- ing plants are introduced to commerce. These various examples are but types of what has been and can be accomplished in a given group of plants. ‘There is nothing mysterious about the subject, so far as the cultivator is concerned. He simply sets his ideal, makes sure that it does not contradict any of the fundamental laws of devel- opment of the plant with which he is to work, then patiently and persistently keeps at his task. He must have good judgment, skill, and inspira-. tion, but he does not need genius. “In the improvement of plants,” writes Henri L. de Vilmorin, “the action of man, much like influences which act on plants in the wild state, only brings about slow and gradual changes, often scarcely. noticeable at first. But if the efforts toward the desired end be kept on steadily, the changes will soon become greater and greater, and the last stages of the improvement will become much more rapid than the first ones.” LECTURE IV. RECENT OPINIONS: BEING A RESUME OF THE INVESTIGATIONS OF DE VRIES, MENDEL, AND OTHERS, AND A STATEMENT OF THE CURRENT TENDENCIES OF AMERICAN PLANT-BREEDING PRACTICE. IN the first and second editions, Lecture IV. was devoted to “ Borrowed Opinions,” being extracts from representative European writings. The chap- ter contained a conspectus of Verlot’s opinions re- specting the production of varieties, as exptessed in his “Sur la Production et la Fixation des¥ ari- éetes dans les Plantes d’Ornement”’; also a rather full transcript of Carriére’s account of bud-varie- ties from his “ Production et Fixation des Vari- étés dans les Végétaux”; and a translation of Focke’s discussion of the characteristics of crosses from Chapter IV. of “ Die Pflanzen-Mischlinge.” Since 1895 a very great change of view has taken place in respect to all the matters discussed in | those papers, although the vexed questions asso- ciated with bud-variation are not yet greatly elu- cidated. It has seemed best, therefore, to devote. this chapter now to the recent opinions rather than to the older opinions. The idea of the “ fixa- tion of varieties” — as a chemist might speak of 143 : 144 RECENT OPINIONS. the fixation of gases or other substances —will not apply to plants. In fact, the production of mere “varieties” is a passing ideal, for we are now endeavoring to produce characters or units. Varieties are not entities, or real units. ‘The point of emphasis has shifted. It is suggestive that the term “ plant-breeding,” rather than the “ production of varieties,” is now current, indicat- ing that we now conceive primarily of a process: this process, when intelligently followed, may pro- duce plants of new value. I. SomME RECENT IDEAS ON THE EVOLUTION OF PLANTs.! There is endless dissimilarity in nature. No two plants and no two animals are exactly alike. There are more plants and animals than can find a place in which to live and thrive. There results a struggle for existence. Those animals or plants which, by virtue of their individual differences or peculiarities, are best fitted to the conditions in which they are placed, survive in this struggle for existence. They are “selected” to live. Those that survive, propagate their peculiarities. By 1 Address before the Society for Plant Morphology and Physi- ology, Washington, December 29, 1902. Printed in Science, March 20, 1903, but now somewhat modified. The greater part of this essay that relates to the De Vriesian views was read and corrected in the manuscript by Professor de Vries. EVOLUTION OF PLANTS. 145 virtue of continued variation, and of continual se- lection along a certain line, the peculiarities may become augmented ; finally the gulf of separation from the parental stem becomes great, and what we call a new species has originated. This, in epitome, is the philosophy of Darwin in respect to evolution of organic forms. It con- tains the well-known postulate of natural selec- tion, the principle that we know as Darwinism. This principle has had more adherents than any other hypothesis of the process of evolution. All recent hypotheses in some way relate to it. A number of them modify it, and some dispute it. The most pronounced counter-hypothesis is also the newest. It is that of Professor de Vries, botanist, of Amsterdam, who denies that natural selection is competent to produce species, or that organic ascent is the product of small differences gradually enlarging into great ones. According to De Vries’s view, species-characters arise sud- denly, or all at once, and they are ordinarily stable from the moment they arise. a. Variation: De Vries. De Vries conceives that variations, or differ- ences, are of two general categories: (1) Va- riation proper, or small, fluctuating, unstable differences peculiar to the individual (only par- L 146 RECENT OPINIONS. tially transmitted to offspring); and (2) muta- tions, or differences that are usually of marked character, appear suddenly and without transition to other forms and are at once the starting-points of new races or species. Variations proper may be due to the immediate environment in which the plant lives. , The mutations are due to causes yet unknown, although these causes are considered to be physiological. Natural selection works on both variations and mutations by eliminating the forms that are least adapted to persist. It is conceived to be a de- structive, not a constructive or augmentative agency. It merely weeds out. We may first consider selection with reference to variations proper. Among variations, or indi- vidual fluctuations, there may be a slight cumula- tive effect of selection, but it is incompetent ever to enlarge the differences into stable character- istics ; and when natural selection ceases to act, the so-called variety falls back into its original form or splits up into other forms. Varieties of this kind are notably indefinable and unstable. It is impossible to “fix” them in any true sense ; selection only preserves them, and when it is removed they perish as varieties. They are rela- tively only temporary and have no effect on phy- logeny. Many of the minor adaptations of plants to the particular conditions in which they chance EVOLUTION OF PLANTS. 147 for the time being to be placed, are of this category. Much of the variation which results in acclimati- zation belongs here. The fluctuating horticul- tural varieties and gardeners’ “strains” are of this kind. This discussion of the effect of cessa- tion of selection recalls Weismann’s panmixia, a name proposed to designate the breaking up of varietal or specific characteristics when natural selection ceases to act. Panmixia is not of itself an original force or an agency; it is merely a name for the results of all the forces or energies which are allowed to assert themselves when the restricting force of natural selection is removed. In De Vries’s view, the progress made by icant: must be maintained by selection. We may next consider selection with reference to mutations. The mutations are practically stable or “fixed” the moment they arise. Of course there may be individual fluctuations or variations proper, amongst plants that have sprung from a mutated individual ; but the main characteristics of the mutations are heritable. An organism is a complex of organs and attributes. Each attribute is a unit. From any unit a new unit may arise by mutation. The origination of a new unit con- stitutes at once a full and important character and marks the organism that possesses it as a new physiological species. Not only one unit, but any number of units, may give rise to mutations ; and 148 RECENT OPINIONS. any one of these new mutations may give rise to other mutations. But the point is, that these mutations, be they great or small, arise by steps, are full formed when they arise, and do not grow or enlarge into other mutations. The mutations are multifarious (all-seitig), occurring apparently at random and in diverse directions, and with- out regard to fitness. They may be either quan- titative or qualitative. Variations proper arise mostly in a definite line. Now, natural selection may weed out mutated individuals as it does mere variant individuals; and thus breaks may arise in the chain, and we have left what we know as taxonomic species. Natural selection, with survival of the fittest, is, therefore, of two categories, at least so far as results are concerned,—that which operates within the species and results in the formation of local minor races, and that which operates between species and results in the formation of a line of ascent. Everywhere and always plants are variable. Now and then and relatively rarely, plants are mutative. Any man who sees two plants, sees variation : there are no two plants alike. Only he who studies and observes critically, sees muta- tion. One must examine a hundred or a thou- sand or ten thousand individuals. In De Vries’s extended’ experiments with Cnothera, only 1.5 per cent of the plants were mutative, and muta- EVOLUTION OF PLANTS. 149 tion is undoubtedly more common in cultivation than in the wild, and the mutated individuals are more likely to persist. The investigator should employ only statistical methods of comparison. He should contrast unit-characters rather than in- dividuals as a whole. Moreover, not only are the numbers of mutating individuals relatively uncom- mon, but the species may not now be in a muta- tive epoch. In other words, there are epochs in the history of the plant when mutations occur. These are the “ mutation-periods” of De Vries. There are epochs of non-mutations, when no progress seems to be making. It may be conceived that some force is withholding or restraining the mutative impulse. This force is what we are in the habit of calling heredity. When heredity is overcome, there arises a “ premutation- period,” in which the mutations are beginning ‘to express themselves ; and eventually the full mutation-period may ap- pear. Heredity and non-heredity, these are the ever opposing and ever contrasting forces in or- ganic life, the one resulting in the survival of the like, the other resulting in the survival of the unlike. One is heredity; the other is variation. One makes for continuity; the other for evolution. No hypothesis of the energy of evolution is per- fect that does not account for both. A theory of heredity, or continuity, must also account for the 150 RECENT OPINIONS. opposite of itself. It is not easy to construct a hypothesis or a metaphor that will accomplish this. The phenomena of continuity and discontinuity were well contrasted by Korschinsky. These phenomena, he conceived, are the results of two antagonistic tendencies. Under normal or usual conditions heredity is the stronger force. The tendency to vary is always present, being predis- posed by environment but not caused by it ; when it gathers the necessary energy it overbreaks the power of inheritance and sudden variations or sports arise, and these sports are the starting- points of evolution. This discontinuous evolu- . tion is called by him heterogenesis. The conceptions of per saltum variations of Korschinsky and De Vries seem to be practically identical. De Vries has carried his work further, into the realm of actual experimental investiga- tion. He studied many species of plants in the hope of finding one or more that might be in its mutation-period. Finally, he chose the common evening primrose, nothera Lamarckiana, and by continual sowing of seeds and raising of great numbers of plants he discovered several truly mutative forms. These forms reproduce them- selves by means of seeds as accurately as accepted species do. He has given some of them specific names. ‘The full experimental history of them is given in the first volume of his brilliant work, EVOLUTION OF PLANTS. 151 “Die Mutationstheorie.” These forms, he con- tends, are true elementary species. That is, they have new specific characters. These characters are heritable. It does not matter whether these characters are large or sinall — they become phylo- genetic. These plants having the new specific characters may not be species in the Linnean or historic or morphological sense, but they are real entities. We must give up the historical view of species when we study the evolution of organic forms. Historic or Linnean species are taxonomic conceptions ; the evolutional or elementary spe- cies are physiological conceptions. The different categories of species, as respects their origin, are given as follows by De Vries : — A. Origin by means of formation of new char- acters, or progressive species-origin. B. Origin without formation of new characters. 1. By the becoming latent (latentwerden) of present characteristics, or retrogressive species-origin. Atavism in part belongs here. 2. By the becoming active (actwirung) of latent characteristics, or degressive spe- cies-origin [ degress, to come down from, - to come out of]. (a) Taxonomic anomalies. (6) True atavism. 3. By means of hybrids. tas RECENT OPINIONS. It will now be seen that the mutation theory of De Vries, which is in some respects a rephrasing and an extending of the old idea of sports, does not of itself introduce any new theory of the dynamics of evolution. It is not a theory of heredity nor of variation. His hypothesis of “ in- tracellular pangenesis”’ carries the explanation of these phenomena one step further back, however. The plant cells give off pangenes. Each of these pangenes divides into two. Ordinarily, these two resemble the parent; but now and then one of them takes on a new character —the two become unlike —and gives rise to a mutation. This hy- pothesis, like Darwin’s pangenesis, is useful as a graphic basis for discussion, whether or no it has real physiological foundation. The most emphatic points of the mutation theory as they appeal to me are these: (1) It classifies variation into kinds that are concerned in evolution and kinds that are not ; and thereby it denies that all adaptation to environment makes for the progress of the race. (2) It denies the power of natural selection to fix, to heap up, or to augment differences until they become truly specific. (3) It separates the results of struggle for existence and survival of the fittest into two categories, only one of which has an effect on phylogeny. (4) It asserts that evolution takes “place by steps, and not by a gradual unfolding of e EVOLUTION OF PLANTS. 153: one form into another, —that it is discontinuous rather than continuous. (5) It enforces the im- portance of critical comparative study of great numbers of individuals. (6) It challenges the validity of the customary conception of species as competent to elucidate the method of evolution. There will arise confusion, in the forthcoming discussions of the theory of discontinuity, as to what is a species; but this confusion is not new. There are two conceptions of species: (1) As taxonomic groups, more or less arbitrarily made for purposes of classification; (2) as real things, marked by recordable differences however small or great, and conceived to be the actual steps in the phylogeny of the race. These categories are so distinct that they would not be confounded ex- cept for the unfortunate circumstance that we use one word (species) for the two. There has been a growing conviction that the two classes must be sharply separated when evolution questions are discussed. Nearly ten years ago I endeavored to combat the species-dogma from the garden point of view, as, in differing ways, others had done be- fore (“Survival of the Unlike,” Essay IV.). The confusion of the two conceptions expresses itself in the terminology of plant-breeding. Some writ- ers define hybrid, for example, as a cross between species; this is the classificatory idea. Others define it to be any cross. The former use of the 154 RECENT OPINIONS. word is more proper merely because it is the his- toric use, originating as a systematist’s concept. The latter idea should have been expressed by a new word. It is for this reason that I have held to the old or systematic definition of hybrid; but there is no appeal against usage, so, while still proclaiming the righteousness of my cause as an easement of my conscience, I strike my colors and henceforth use the word hybrid for a cross of any kind or degree. How often does mere language confuse us ! | From an argumentative point of view, it will be difficult to determine, in a given case, just what are variations and what mutations, for these cate- gories are separated not by any quantitative or qualitative characters —the “step” from one to the other may be ever so slight — but by the test that one kind is fully heritable and the other only partially so. If a mutation is to be defined as a heritable form, then it will be impossible to con- trovert the doctrine that evolution takes place by mutation, because the mutationist can say that any form that is inherited is by that fact a mutation. This will be equivalent to the position of those who, in the Weismannian days, denied the trans- mission of acquired characters, but defined an acquired character to be one that is not transmis- sible. However, it is to be hoped that the dis- cussion of the mutation theory will not degenerate EVOLUTION OF PLANTS. ‘Lie into a mere academic debate and a contention over definitions. Professor de Vries himself has set the direction of the discussion by making actual experiments the test of the doctrine. There will be confusing points, and times when we shall dis- pute over particular’ forms as to whether they are variations or mutations; but every one who has studied plants from the evolution point of view will be prepared to believe that species do origi- nate by mutation. De Vries’s work will have a profound and abiding influence on our evolution philosophies. For myself, I am a Darwinian, but I hope that I am willing to believe what is true, whether it is Darwinian or anti-Darwinian. My own belief is that species do originate by means of natural selection, but that not all species so originate. b. Heredity: Mendel. De Vries made a thorough search of the litera- ture of plant evolution. In an American publica- tion! he saw a reference to an article on plant 1The following extract from a recent letter from Professor de Vries (printed here by permission) will explain the refer- ence in the text: ‘‘ Many years ago you had the kindness to send me your article on Cross-Breeding and Hybridizing of 1892; and I hope it will interest you to know that it was by means of your bibliography therein that I learnt some years afterwards of the existence of Mendel’s papers, which now are coming to so high credit. Without your aid I fear I should not have found 156 RECENT OPINIONS. hybrids by G. Mendel, published in 1865 in the proceedings of a natural history society of Brinn in Austria. On looking up this paper he was astonished to find that it discussed fundamental questions of hybridization and heredity, and that it had remained practically unknown for a genera- tion. In 1900 he published an account of it, and this was soon followed by independent discussions by Correns, Tschermak, and Bateson. In May, 1900, Bateson gave an abstract of Mendel’s work before the Royal Horticultural Society of Eng- land; and later the society published a translation of Mendel’s original paper. It is only within the present year, however (1902), that a knowledge of Mendel’s work has become widespread in this country. Perhaps the agencies that are most responsible for dissemination of the Mendelian ideas in America are the instruction given by Webber and others in the Graduate School of Agriculture at Columbus last summer, and the prolonged discussion before the International Conference on Plant-Breeding at New York last fall (1902). Lately, several articles on the sub- ject have appeared from our scientific press. them at all.”” My reference to Mendel in the bibliography referred to was taken from Focke’s writing. I had not seen Mendel’s paper. The essay, ‘‘ Cross-Breeding and Hybridizing,”’ forms Chapter II. of the present book ; but the bibliography that accompanied it was not reprinted until the second edition of the book. EVOLUTION OF PLANTS. Ld57 Mendel’s work is important because it cuts across many of the current notions respecting hybridization. As De Vries’s discussions call a halt in the current belief regarding the gradual- ness and slowness of evolution, so Mendel’s call a halt in respect to the common opinion that the results of hybridizing are largely chance, and that hybridization is necessarily only an empirical sub- ject. Mendel found uniformity and constancy of action in hybridization, and to explain this uni- formity he proposed a theory of heredity. | One of the most significant points connected with Mendel’s work is the great pains he took to select plants for his experiments. He believed that hybridism is a complex and intricate subject, and that, if we are ever to discover laws, we must begin with the simplest and least complicated problems. He was aware of the general belief that the most diverse and contradictory results are likely to follow any hybridization. He con- ceived that some of this diversity may be due to instability of parents rather than to the proper results of hybridizing. He also saw that he must exclude all inter-crossing in the progeny. Fur- thermore, the progeny must be numerous, for, since incidental and aberrant variation may arise in the plants, it is only by a study of averages of large numbers that the true results of the hybrid- izing are to be discovered. Moreover, the study 158 RECENT OPINIONS. must be more exact than a mere contrasting and comparing of plants: character must be compared with character. The garden pea seemed to fulfil all the require- ments. Mendel chose well-marked horticultural races or varieties. These he grew two years before the experiment proper was begun in order to determine their stability or trueness to type. When the experiments were finally begun, he used only normal plants as parents, throwing out such as were weak or aberrant. Peas are self- fertile. It was to be expected that under such conditions the hybrid offspring would show uni- formity of action; and it did. In order to study the behavior of the hybrids, it was necessary to choose certain prominent marks or characters for comparison. Seven of these characters were selected for observation. These marks pertain to seed, fruit, position of flowers, and length of stem, and they may be assumed to be representative of all other characters in the plant. These characters were paired (practically opposites), as long-stem vs. short-stem, round-seed vs. angular-seed, inflated-pod vs. constricted-pod. They were “constant” and “differentiating.” Of course every parent plant possessed one or the other of every pair of contrasting characters; but in order to facilitate his studies, Mendel chose a special set of parents to illustrate each character, EVOLUTION OF PLANTS. 159 studying seed-shape in one set of hybrids, seed- color in another, pod-shape in another; in this way he avoided complication in the results. Since it is not my purpose to discuss Mendel’s work in detail, but only the general significance of its results, as they appeal to me, I need not describe these characters here. It will be sufficient if I choose only one, the shape of the seed. | The seed-shape characters were roundness and angularity — the former being the “smooth” pea of gardeners and the latter the “wrinkled” pea. Let us suppose that twenty-five flowers on round- seeded plants were cross-pollinated in the summer of 1900 with pollen from angular-seeded plants, or vice versa, and that an average of four seeds formed in each pod. With the death of the parent plants the old generation ended, and the 100 seeds that matured in 1900—the year in which the cross was made — began the next gen- eration; and these 100 seeds were hybrids. Now, all these 100 seeds were round. Roundness in this case was “dominant.” (Dominance pertain- ing to the vegetative stage of the plant of course would not appear until 1901, when the seeds “orow.”) These seeds are sown in the spring of 1901. If each seed be supposed to give rise to four seeds — or 400 in all—this next generation of seeds (produced in 1901) will show 800 round and 100 angular seeds. That is, the other seed- 160 RECENT OPINIONS. shape now appears in one-fourth of all the prog- eny; this character is said to have been ‘“reces- sive’ in the first hybrid generation. If the 100 angular seeds, or recessives, are sown in 1902, it will be found that all the progeny will be angular- seeded or will “*come true”; and this occurs in all succeeding generations providing no crossing takes place. If the 300 round seeds, or domi- nants, are sown in the spring of 1902, it will be found that 100 of them produce dominants only, and that 200 of them behave as before — one- fourth giving rise to recessives and three-fourths to dominants ; and this occurs in all succeeding generations providing no crossing takes place. In other words, the three-fourths of dominants in any generation are of two kinds, — one-third that produce only dominants, and two-thirds that are hybrids. That is, there is constantly appearing from the hybrids one-fourth part that are re- cessives, one-fourth part that are constant domi- nants, and one-half part that are dominants to all appearances, but which in the next genera- tion break up again into dominants and reces- sives. ‘This one-half part that breaks up into the two characters are the true hybrids; but they are hybrids only in the sense that they hold each of the two parental characteristics — roundness and angularity — in their purity and not as blends or intermediates; and these two characteristics EVOLUTION OF PLANTS. 161 reappear in all succeeding generations in a definite mathematical ratio. Proportionally, these facts may be expressed as follows: — 1900. 1901. 1902. 1903. 4 D———————16 D oe Ceres c 1D 2D 4D 1 seed 2D 14D {8p 2R 8R 1 R————4 R———————16 R It will be seen that two-thirds of the dominants break up the following year into one-fourth con- stant dominants, one-fourth recessives, and one- half that again break up, the half that break up being the hybrids. This formula for the hybrids is Mendel’s law. In words, it may be expressed as follows: Differentiating characters in plants reappear in their purity and in mathematical regu- larity in the second and succeeding hybrid oft- spring of these plants; the mathematical law is that each character separates in each of these gen- erations in one-fourth of the progeny and there- after remains true. In concise figures, it is expressed as follows: 1D:2DER:1 £. mM 162 RECENT OPINIONS. 1Dand1R come true, but DF# breaks up again into dominants and recessives in the ratio of 3 to 1. Mendel found that this law holds more or less for the other characters that he studied in the pea, as well as for the seed-shape. He did not con- clude, however, that it holds good for all plants, . but left the subject for further investigation. He himself found different results in Hieracium. It will be seen at once that it will be a very difficult matter to follow this law when many characters are to be contrasted, particularly when the char- acters are merely qualitative and grade into each other. ; The dominant characters pertain to either parent: some of them may come from the mother and some from the father. When this roundness is dominant from the male parent, it falls under the domination of what we commonly know as xenia, or the immediate effect of pollen; when it is from the female parent, there is no xenia. In the case of the pea, the seed-content is embryo and we are not surprised if there is xenia. In those plants in which the embryo is embedded in endosperm, however, it would seem to be difficult to account for xenial dominance, unless there is double fecundation, as appears to be the case in Indian corn, as pointed out by De Vries, Webber,} 1 Bull. 22, Div. of Veg. Phys. and Path., U. S. Dept. Agric., 1900, EVOLUTION OF PLANTS. 163 and others. It looks as if the question of domi- nance would introduce a new point of view into the study of xenia. At all events, the word xenia must be very clearly re-defined. There is now a strong tendency to restrict the use of the word to designate only those effects occurring in parts lying outside the embryo. Which characters will be dominant in any spe- cies we cannot determine until we perform the experiment; that is, there is no mark or attribute which distinguishes to us a priort a dominant or a recessive character. However, the mere fact as to whether the one or the other character is dominant is relatively unimportant, for constant dominance is no more a regular behavior than - recessiveness is. In various subsequent experi- ments it has been found that even when marked dominance is not shown in the first product, the hybridization may follow the law in essential numerical results. The really important points are: (1) That the characters typically remain pure or do not blend, and (2) that their reappear- ance follows a numerical order. After finding such surprising results as these, Mendel naturally endeavored to discover the rea- sons why. ‘The product of his speculations is the theory of gametic purity (to use our present-day terminology), which is a partial theory of heredity. Every plant is the product of the germ or female 164 RECENT OPINIONS. cell fertilized by the sperm or male cell. When constant progeny is produced it must be because the two cells, or gametes, are of like character. When inconstant progeny is produced, it must be because the sperm cell is of one character and the germ cell of another. When these unlike gametes come together they will unite according to the law of mathematical probabilities, one-fourth of those of each kind coming together and one-half of those of both kinds coming together. If A and B represent the contrasting parental characteris- tics, they would combine as — A+ A= A? A+ B= AB Bt+A=BA B+ B= PB A? and B? are equivalent only to A and B. Since both of the opposed or contrasted characters cannot be visible at the same time, we have the following : — A Ad A? B in which small 6 represents the character that for the time being is not able to express itself, or is recessive, and large B represents the same charac- ter fully expressed. In these gametes the unit characters of the plants that bear them are pure. Even in hybrid EVOLUTION OF PLANTS. 165 plants the pollen grains and the egg cells are not hybrids. According to this hypothesis of gametic purity, therefore, hybrids follow natural and numer- ical laws; but these laws are always obscured by new crossing. ‘True intermediate characters do not occur. If new characters appear, it is because they have been recessive or latent for a genera- tion, or because the plant has varied from other causes; they are not the proper results of hybridi- zation. We may suppose that a new character that appears because of effect of environment may be impressed on the gamete and thereby be perpet- uated. The results of hybridization, according to the Mendelian view, are not fundamentally a mere game of chance, but follow a law of regularity of averages; but the results are so often masked that it is sometimes impossible to recognize the law. It is a question, of course, whether the propor- tional results secured by Mendel and others express a biological principle, or whether they are only the numerical proportions that may be adduced from the averages of large numbers of combinations — whether these combinations are of gametes, or let- ters, or words, or figures. It is a fundamental necessity that certain proportions follow from “chance” combinations often repeated. But whether the “ theorem of probabilities” can express a real biological fact may well be doubted. Per- haps the basis of heredity is of a very different 166 RECENT OPINIONS. order from the mechanico-physical conceptions that we habitually apply to it. Mendel’s law of heredity is recently stated as follows by Bateson and Saunders: ‘ The essential part of the discovery is the evidence that the germ- cells or gametes produced by cross-bred organisms may in respect of given characters be of the pure parental types and consequently incapable of transmitting the opposite character; that when such pure similar gametes of opposite sexes are united together in fertilization, the individuals so formed and their posterity are free from all taint of the cross; that there may be, in short, perfect or almost perfect discontinuity between these germs in respect of one of each pair of opposite characters.” This, in barest epitome, is the teaching of Men- del. This teaching strikes at the root of two or three difficult and vital problems. It presents a new conception of the proximate mechanism of heredity, although it does not present a complete hypothesis of heredity since it begins with the gametes after they are formed and does not ac- count for the constitution of the gametes, nor the way in which the parental characters are impressed upon them. This hypothesis will focus our atten- tion along new lines, and I believe will arouse as much discussion as Weismann’s hypothesis did ; and it is probable that it will have a wider inilu- EVOLUTION OF PLANTS. 167 ence. Whether it expresses the actual means of heredity or not it is yet much too early to say; but this hypothesis is a greater contribution to science than the so-called “ Mendel law” as to the nu- merical results of hybridization: the hypothesis attempts to explain the “law.” ! One great merit of the hypothesis is the fact that its basis is a morphological unit, or at least an appreciable unit, not a mere imaginary concept. This unit should be capable of direct study, at least in some of its phases. It would seem that the Mendelian hypothesis would give a new direc- tion to cytological research.? It is yet too early to say how far Mendel’s law applies. We shall need to re-study the work that has been done and to do new work along more definite lines. There are relatively few results of experiments that can be conformed to Mendel’s law, because the data are not complete enough or not made from the proper point of view. We should expect the fundamental results to be masked when the plants with which we work are themselves unstable, when cross-fertilization is allowed to take place, or when the pairs of con- 1 This, I take it, is also the opinion of Bateson, the leading interpreter of Mendel in English; for he calls his new book on the subject (1902) ‘‘ Mendel’s Principles of Heredity,’’ as if the heredity idea were greater than the hybridization idea. 2 See, for example, ‘‘ A Cytological Basis for the Mendelian Laws,”’’ Bull. Torr. Bot. Club, 29, 657 (1902), by W. A. Cannon. 168 RECENT OPINIONS. trasting characters are very numerous and very complex. Marked numerical results have been found by various workers in different fields, in this country notably by Spillman in hybrid wheats. Mendel was able to discover the numerical law because he eliminated nearly all the confusing contingencies. In the discussion of every bold new hypothesis, we are in danger of becoming partisans, taking a stand either for it or against it. The judicial attitude is also the scientific one. We want to know. Two processes are now going forward in the discussion of Mendel’s law,—one the explaining away of “exceptions,” the other the endeavoring to find the true place of the law in the scheme of evolution. ‘The one is primarily an effort to up- hold the law; the other is primarily a desire to adjudge it. One is an effort to apply it uni- versally ; the other to determine whether it is universal. Already so many adjustments have been made of the Mendelian principles that it is becoming difficult to determine what Mendelism is. These cases are typical of the discussions on almost every vital question connected with evolu- tion. At the hard places we make a supposition and modify the hypothesis in the face of a fact. We can prove anything by supposing. The results of Mendel’s work have two impor- tant bearings on current evolution discussion: (1) EVOLUTION OF PLANTS. 169 on the part that hybridization plays under natural conditions in the evolution of the forms of life, and (2) the part that it plays in plant-breeding. In the former category his work gives a hint of defi- niteness to the role of hybridization in the origi- nation of new combination-forms. In the latter category it is difficult as yet to measure its im- portance, since extended applications to practice have not been made, and since, also, the Mendelian principles have been themselves so much the sub- ject of debate and definition that it is difficult to distinguish between Mendelism and the endeavor to make the Mendelian suggestions fit our present- day knowledge. In discussing the application of Mendel’s work to plant-breeding, I desire to keep in mind the work that he did with peas, upon which the “ Mendel law” chiefly rests. c. Application to Plant-Breeding. The wildest prophecies have been made in re- spect to the application of Mendel’s law to the practice of plant-breeding, for the mathematical formulas express only definiteness and precision. Unfortunately, the formulas cannot express the indefiniteness and the unprecision which even Mendel found in his work. My own feeling is that the greatest benefit of Mendel’s work to the plant-breeder will be in improving the methods of 170 RECENT OPINIONS. experimenting. We can no longer be satisfied with mere “trials” in hybridizing: we must plan the work with great care, have definite ideals, “work to a line,” and make accurate and statisti- cal studies of the separate marks or characters of plants. His work suggests what we are to look for. Beyond this I do not see how the original Men- delian results will greatly modify our plant-breed- ing practice. The best breeders now breed to unit characters, for this is the significance of such expressions as “avoid breeding for antagonistic characters,’ “breed for one thing at a time,” “know what you want,” “have a definite ideal,” “keep the variety up to a standard.” In certain classes of plants the Mendelian laws will be found to apply with great regularity, and in these we shall be able to know beforehand about what to expect. The number of cases in which the law or some modification of it applies, is being extended daily, both for animals and plants ;1 but in practice we shall probably find as many exceptions to the for- mulas as confirmations of them, even though the exceptions can be explained, after we find them, by Mendel’s principle of heredity. 1 See, for example, Bateson and Saunders’s report to the Royal Society on heredity. A recent paper by Cuénot (Archives of Exper. and Gen. Zodl., 1903) gives confirmatory results on hybrid mice, with discussions of the nature of dominance. This line of investigation is likely to be very popular for the next few years. EVOLUTION OF PLANTS. Vig It has been said that we shall soon be able, as a result of Mendel’s discoveries, to predict varieties in plant-breeding. Before considering this ques- tion, we must recall the fact that a cultural variety is a succession of plants that has characters suffi- ciently marked and uniform to make it worth cultivating in place of some older variety. Now and then it may be worth while to introduce some new energy or new trend into a general lot of offspring by making wholesale crosses, not ex- pecting ever to segregate any particular variety or strain from the progeny ; but these cases are rare, and the gain is indefinite and temporary. So far as our knowledge at present goes, I see no warrant for the hope that we can predict varieties with any degree of exactness, at least not beyond a very narrow effort. Following are some of the -reasons that seem to me to argue against the probability of useful prophecy of varieties so far as the Mendelian results are concerned: (1) We do not know what plants will Mendelize until we try. (2) Even in plants that do Mendelize, only half of the offspring have stable characters. But we cannot predict for even this half, for it is impossible to determine beforehand which seeds showing dominant characters (and these are three- fourths of the offspring) will “come true.”” Domi- nance, as we have seen, is of two kinds in respect to its behavior in the next generation, — constant 172 RECENT OPINIONS. and hybrid ; and the hybrid dominance, which is twice as frequent as the other, breaks up into con- stant dominance, hybrid dominance, and recessive- ness. (3) Mendel’s law deals primarily with mere characters, not with a variety or with a plant as a whole. Every plant is a composite of a multitude of characters, and from the plant-breeder’s point of view there may be as many undesirable characters as desirable ones. No plant is perfect ; if it were, there would be no need of plant-breeding. The breeder wants to preserve the desirable characters or traits and eliminate the undesirable ones; but under the strict interpretation of Mendelism this may be difficult and perhaps impossible. The one germ gamete and the one sperm gamete that unite to make the new plant, each contain all the alter- native parental characters; these various char- acters reappear in the offspring, and all that the breeder gains is a new combination or arrangement of characters, and the undesirable attributes may be as troublesome as before. (4) The breeder usually wants wholly new characters as well as re- combinations of old ones, or he wants augmented characters, and these lie outside the true Mende- lian categories. For example, a carnation grower wants a four-inch flower, but he has only three-inch flowers to work with, and augmentation of charac- ters is no part of the original Mendelian law. Per- haps these augmented and new characters are to EVOLUTION OF PLANTS. 173 be got by means of ordinary variation and selec- tion, or other extra-crossing means; but we know, as a matter of fact, that augmented characters do sometimes appear in hybrids. (5) New and un- predictable characters are likely to arise from the influence of environment or other causes, and very likely these may be recorded in thé gametes and vitiate the final results. (6) Variability itself may be a unit character and therefore pass over. There is probably such a thing as a “tendency to vary,’ wholly aside from the fact of variation. (7) Many of the plants with which we need most to work in plant-breeding are themselves eminently variable and the results, even if there is true Men- delism, may be so uncertain as to be wholly unpre- dictable. (8) Many plants with which we must work will not close-fertilize. Some of them are moneecious or dicecious. Even if there is gametic purity in such plants, the probability is that the fact can be discovered only by a long line of scien- tific experimenting for that particular purpose and not by the work of the man who desires only to breed new plants. (9) A cultural variety, in any true acceptation of the term, is a series of closely related plants having a pedigree. It runs back to one individual plant, from which propagation has been made by seeds or asexual parts. Now, one can never predict just what combination of characters any plant will have, even though it be 174 RECENT OPINIONS. strictly Mendelian. A person might have a thou- sand hybrids of which no one plant shows any two characters in the proportion of 3 to 1 (both seed- characters may appear in the same pod or in dif- ferent pods on the same plant), let alone all the characters as 3 to 1 or in other definite relation ; and yet the total average numerical results might conform exactly to the Mendelian law. Mendel’s law is a law of averages. The very fact that one must employ such large numbers to secure the numerical results shows that we cannot predict as to individuals. For example, in ten plants of pea, Mendel found the following ratios in respect to seed-shape and seed-color: — Shape. Color. Shape. Color. 3.75: 1 pe Ad Bae | 4.33:1 3.33 :1 3.387 :1 4.57:1 3.66 :1 2.43:1 3.43 :1 2.80 :1 2.20 :1 4.88: 1 1.90 #1 2.00 2-1), 4.66:1 3. 616m 2:01 : 1 1.85: 1 3.57 : 1 2.44:1 Mendel reports one instance in which the ratio in seed-shape was 21 to 1, and another of 1 tol. He also reports instances of seed-color of 32 to 1, and 1 tol. It has been said that, because of Mendel’s work, we shall be able to produce hybrid varieties with the same certainty that we produce chemical compounds. Now, a plant is made up of many combinations of many units, and these combina- tions are the results of mathematical chance or probability. Of course, when the offspring are EVOLUTION OF PLANTS. 175 numerous, all possible combinations are likely to occur ; but these occurrences are essentially for- tuitous. Chemical compounds are specific entities in which the parts combine by necessity with defi- niteness. The comparison, as it appeals to me, is fallacious and the conclusion unsound. We must remember that there are whole classes of cases of plant-breeding that do not fall under hybridization at all. Granting the De Vriesian view that selection is incompetent to produce species from individual fluctuations, it is never- theless well established (and admitted by De Vries) that very many of our most useful cultural varie- ties have been brought to their present state of perfection by means of selection; and by selection they are maintained in their usefulness. Selection will always be a most important agency in the hands of the gardener and the plant-breeder — none the less so now that we have challenged its role in the evolution of the plant kingdom. For the time being, the new discussions of hybridiza- tion are likely to overshadow all other agencies in plant-breeding; but selection under cultivation is as important now as it was in the days of Van Mons and Darwin. d. Interpretation of Hybridism. It is probable that the clearest insight into this whole new question of hybridization is to be 176 RECENT OPINIONS. got by following the work of De Vries. The concluding parts of the second volume of his ‘“‘ Mutationstheorie,” a volume devoted wholly to hybridization, is on the press at this moment. The Mendelian laws are fully discussed in this volume, but the summary conclusions may be pre- sented here. De Vries had been working at hybridization long before he discovered Mendel, and had arrived at practically the same results ; he had also arrived at other results that are not Mendelian. De Vries denominated the law of numerical segregation as the “law of separation of characters in crosses.” Like Mendel, he had found that merely to cross “varieties” or “species” is of no avail in the study of fundamental prob- lems; for the varieties and species that we know are mere systematic groups with characters of all kinds and degrees. We must cross 8 characters or units, not species. I pa Every unit-character De Vries conceives to be represented in the germ bya pangene. This pan- gene may be active, in which case the character appears in the plant; or it may be dormant, in which case the character is not visible, or for the time being is lost. Active pangenes may at any time become latent, or latent ones may. become active. Mendel’s law results bia an interchange of contrasting characters. True physiological. or EVOLUTION OF PLANTS. ar elementary species differ from each other by new unit-characters. They have arisen by progressive mutation. The characters are not contrasting or differentiating. One species has one kind of pan- gene, another species another kind of pangene. On combining these there can be no interchange of characters, and, therefore, no Mendelism. There is nothing for one character to exchange against the other. In the case of true progressive muta- tions, therefore, upon which the progress of the plant race depends, there can be no Mendelizing. Hybrids in these cases are intermediates, or else follow only one or the other of the parents. Now, varieties differ from true mutative species in the fact that they have contrasting characters. These characters are represented by their special kinds of pangenes. ‘The pangene may be active or passive. That is, the variety may be a variety because one or more of its characters has become latent (retrogressive), or because characters have become active (degressive). When these charac- ters are crossed, there is an interchange of the pairs. Both parents bear the same unit-character, but this character is active in the one and dormant in the other. The hybrid receives an active pan- gene from one parent and a similar but inactive pangene from the other. When these two units unite, the calculus of chance determines that there shall reappear in the second generation equal num- N 178 RECENT OPINIONS. bers of both the parental units, and a half of the whole that are still hybrids and break up in the same ratio in the third generation. ‘That is, true Mendelism is confined to crossings of retrogressive and degressive varietal characters. There are, therefore, two general classes of hy- brid formation: the isogons, giving rise to crosses “in which two antagonistic parental characters reappear in numerical order (Mendelian cases); anisogons, giving rise to crosses in which two antagonistic characters sometimes separate un- equally, but ordinarily do not separate at all. When only one parent is represented in the off- spring, we have the “unisexual crosses” of Macfar- lane or the “false crosses” of Millardet. These are cases in which there are no true contrasting characters. Spillman has recently explained the false hybrids by supposing that the plants in this case are self-fertile and sterile with other pollen. That is, A is fertile with A, B with B, but A is not fertile with B nor B with A; there results, therefore, no true crossing. This hypothesis should be capable of experimental proof or dis- proof. The isogon hybrids are of all degrees of com- plexity, and classification of them will at once show how far we have already got away from the old systematic idea of variety-hybrids and species- hybrids. Hybrids between plants that differ only EVOLUTION OF PLANTS. 179 in one unit-character are monohybrids. ‘These are the ones in which the numerical results are most clearly traced, but they are also exceedingly rare. Those in which two unit-characters are concerned are dihybrids. In these the combination series gives four different kinds of offspring. So there are trihybrids, giving eight possible combinations, tetrahybrids, and so on to polyhybrids; and in every succeeding grade the difficulties of statistical and comparative studies increase. Of how many characters is a plant composed ? e. Conclusion. Now, in conclusion, what are the great things that we have learned from these newer studies ? (1) In the first place, we have been brought to a full stop in respect to our ways of thinking on these evolution subjects. (2) We are compelled to give up forever the taxonomic idea of species as a basis for studying the process of evolution. (3) The experimental method has finally been completely launched and set under way. Labora- tory methods, comparative morphology, embryo- logical recapitulation, life-history studies, ecological investigations —all these means are likely to be overshadowed for a time by experiments in actu- ally growing the things under conditions of control. (4) We must study great numbers of individuals ‘WVCUALSWY ‘SNHCUVY) IVOINVLOG ‘VHHHLON GD 20 SHINHAG SQOIUVA ANV NUOD ONIMOHS ‘NAGUVYH) INAWIYAAX | 8,SaIaA AQ AOSsH#Aoug NI ‘ADVD AH, “4 my) 34 ari’ al 7 EVOLUTION OF PLANTS. 181 and employ statistical methods of comparison. (5) The doctrine of discontinuous evolution is now clearly before us. (6) We are beginning to find a pathway through the bewildering maze of hybridization. Mendelism in Wheat. In order that I may present a specific example of evident Mendelian results, I have asked W. J. Spillman, agriculturist of the Department of Agriculture, to explain some of his experiments with wheat.t Mr. Spillman independently dis- covered numerical results, before the knowledge of the Mendelian experiments had become gen- erally known. “The photograph (p. 183) shows three genera- tions of one of my hybrid wheats. Of the three ~ heads in the upper row, the left-hand one is the male parent (variety Valley); the right-hand one is the female parent (variety Little Club); and the middle one is the hybrid. The second row shows the second generation, and the third row the third generation. Of the six types in the second gener- ation, the following points are important: Each type was present in a certain proportion, which was approximately the same as in thirteen other similar cases, and the average of these fourteen cases closely approximated the theoretical numbers 1 For illustration in maize, see p. 227, 182 ' RECENT OPINIONS. called for by Mendel’s hypothesis of the disjunc- tion of parental characters. ‘The three at the left, being bearded, possess a character which was latent in the first generation. The fact that the beards show in these three indicates that the opposite char- acter is absent, and they should therefore remain bearded in succeeding generations. That is, they are no longer hybrid with reference to this charac- ter. It will be observed that this was actually the case, for no beardless heads appeared in the progeny of either of these three (see lower row, first five - heads). The following diagram will show the char- acter of each of the six types in row two. In this diagram the letters have the following meanings: — B= bearded (written 6 when latent). S = smooth (not bearded). I = long heads. C = club heads (short). I = intermediate in length of head. (The hybrid was interme- diate in this respect. ) Parents. First Generation. Second Generation. 1 BL . 2 BI BL 1 BC 2 SdL 4 SbI 2 SbC 1 SL 2 SI mont 18C 16 SbI tie sR ¥ v4 ——~€ ‘> — / Ch ELKE << gtet op ERR RE KEE owe TT _—~“€ THREE GENERATIONS OF HYBRID WHEAT. A1=male parent, A 2= the hybrid, A3= female parent. B 1-6= the progeny of A2. C1=progeny of B1. C 24= progeny of B2. C5=progeny of B3. C6 and 7 = progeny of B4. C 8-13= progeny of B5. C 14 and 15 = progeny of B 6. The results in the fourth generation, available too late to include in the photograph, indicate that B 2 and B 3, while not always separable on external appearances, are absolutely different, the one being hybrid, the other pure. 184 RECENT OPINIONS. “This diagram shows the nine types called for by Mendel’s theory. Of these, BL, BC, SZ, and SC are no longer hybrids —at least they have no latent characters, and will therefore reproduce true to seed. Of the remaining five types, BZ and ST are hybrid only with reference to length of head, and S6L and SOC only with reference to beards ; while SdJ is hybrid with reference to both char- acters, as in the preceding generation. “Tt will readily be seen that the types BZ and BC can be separated from the other seven by ex- ternal appearances, and obtained -in a pure state. BL is the type shown at the left in the second row in the picture, and all its progeny was like it, showing that it conformed to theory. BC is the type shown at No. 3 in the second row of heads; being pure, it should reproduce itself true to type, which it did, with an easily explained exception to be noted below. The type BZ (shown at No. 2, row 2) being hybrid with reference to length of head, should produce again all the types based on this character, and it did this as is seen in heads 2-4, row 3. Referring again to the above diagram, it will be seen that the types SZ and SéZ cannot be distinguished by external characters. SZ will of course reproduce true to type, while SOL will produce SZ, SbL, and BL. Now SL and SbL being mixed together in the selection made in the second generation, we should find a large percent- EVOLUTION OF PLANTS. 185 age of SZ mixed with some S6LZ from which ‘it cannot be distinguished, and a small percentage of BL in the third generation. Heads 6 and 7, row 8, show that the types called for actually occurred. Types Sf and S6J of the diagram appear alike ex- ternally, and were therefore selected together in the second generation (see head 5, row 2). Now SI should produce the types SZ, SZ, and SC, while SéI should produce all nine types again (these nine types can be separated only into six by externat appearance). It is therefore seen that the group represented by head 5, row 2, should produce all six, types again. Heads 8-15, row 3, show these types. Types SbC and SC of the diagram are alike externally, and were hence selected together last year. Ofthese SC should produce only SC, while S6C should produce SC, S6C, and BC. But since SC’ and SOC look alike, the progeny of these two types should show only SC and BC. The last two heads in row 8 show that this actually occurred. “In the single set of heads shown, there were two easily explained exceptions to theory. It will be seen that heads 2 and 3, row 2, differ only in length; now the group represented by head 2 varied in length from that of 1 to that of 3. In separating 2 and 3, it might easily happen that some of 3 should be placed with two. In this case the progeny of 8 would show a few heads like 1, 186 RECENT OPINIONS. and this was the case. I have shown in the photo- graph only the heads called for by theory, for it would only lead to confusion to include the excep- tions which would probably not have occurred if 2 and 83 of row 2 had been accurately separated last year. Again, in the progeny of the group repre- sented by head 5, row 2, only five of the six types shown (row 8, heads 8-13) were found in this par- ticular case, though all six were found in most of the others. As the missing type should constitute only 4% per cent of the group, and as it differed from one of the others only slightly, it is possible that it was included with the related type when the selections were made. “T have not yet seen the data for the third gen- eration of all these wheats, but those which are at hand are decidedly interesting. The following are the data for the third generation of the cross between Jones Winter Fife (male) and Little Club (female). The Fife is long-headed, and has velvet chaff (V); the Club short-headed, and has glabrous chaff (G). Velvet proved to be dominant over glabrous, and the hybrids were intermediate in length. Type I. of the second generation included the two types VZ and VgZ, since these could not be distinguished by external appearances. Seed of Type I. produced in the third generation : — 1 Data for the fourth generation, now at hand, agree well with the theory. EVOLUTION OF PLANTS. 187 Plot. Percentage of Types. L=VL. Il. = GL. 1 87 13 2 BL 19, Theory 854 162 The figures for the remaining five second-genera- tion types are as follows : — Type IL = GL. Percentage of Types. Plot. Jie 1 100 2 100 Theory 100 Type III. = VJ and VoL. Plot. ‘ II. III. IV. V. Wie A 21 7 38 9 20 5 Bs opie), 8, BR. gts AR Theory 203 4} 412 81 203 42 Type IV.=G1. Plot. i: IW WE 1 28 52 20 2 51 40 22 Theory 25 50 25 Type V.= VC and VgC. Plot. fe II. V. vi. 1 2.4 80.0 17.6 2 4.7 2.6 79.8 13.9 Theory 851 162 Type VI. =GC. Plot. II. Wel. 1 7.7 92.3 2 100.0 188 RECENT OPINIONS. ‘The only departures from theory of any conse- quence in these data are the occurrence of small amounts of Types I. and II. in the progeny of V., and of II. in the progeny of VI. Now, Type V. of the second generation (VC and Vqg(C) differed from Type III. (VZ) only in being slightly shorter. If a few individuals of III. had been included in V. in separating the types of the second generation, we should have the actual result obtained in the third generation. Likewise, Type VI. of the sec- ond generation (GC) differed from II. (GJ) in the same manner. Evidently a few plants of II. got into the Type VI. last year, and thus gave the results shown. “These hybrids are now under the care of Pro- fessor E. E. Elliott, of Pullman, Washington ; and from a recent letter I infer that spring character in wheats is dominant over the winter character, as a large majority of the fourth generation have the spring character (all the club wheats used were spring wheats). “The original purpose of this work was to pro- duce a winter-club wheat, a type much needed in eastern Washington. It is probable that the effort was successful, but the invariable interruptions to work that follow a change of personnel in the workers has delayed the final results. “Tt now seems probable that Mendel’s theory is true, at least in these wheats. If this theory ON HYBRIDIZATION. 189 should prove generally true, the following most important fact follows: If the individuals of the second generation are numerous enough, there is present in this generation every possible combina- tion of the parent characters, and, most important of all, every one of these combinations is present in some individuals in a fixed form that will re- produce true to seed. The fixed forms can easily be separated from the others by treating each plant of the second generation as an individual, and noting which of them reproduce true to seed. “Tt should further be noted that the forms not already fixed in the second year will, in later gen- erations, gradually break up into the same fixed forms as those occurring in the second generation. It is therefore possible to secure in the third gen- eration all the pure fixed forms that can be secured from a hybrid. (Close fertilization is assumed in all cases.)” II. On HYBRIDIZATION. By Hueco De Vries. (Written expressly for the third edition of ‘‘ Plant-Breeding.’’) Hybrids are ordinarily said to be intermediate between their parents. But by a closer inspection this relation appears to be of a complex nature; for the intermediate state may be such in regard 190 RECENT OPINIONS. to the single characters, or may be the result of the mixing of pure or nearly pure paternal and maternal characters in the same individual. Gen- erally it is said that specific characters are handed over in a more or less reduced degree, but that racial peculiarities take either to the father or to the mother. The difference between specific and racial marks is of course as much a question of personal appre- ciation as is the hmit between species and races or varieties itself. But it is clear that the behavior of hybrids, both natural and artificial, does not depend upon our appreciation of the facts, but on the facts themselves. We have therefore to search for a character which is independent of the syste- matic value given to the groups in question. — Such a criterion is yielded by the theory of the origin of species by mutations. Of course the theory only indicates the principle, and much work will have to be done before it will be pos- sible to apply it in all individual cases. But a clear conception of the ruling idea will point to the direction in which the experiments will have to be made, and it will assist the hybridist in a more thorough comparison of the hybrids and their parents. Moreover, a consideration of the characters of the parents from the new point of view will enable him, in the majority of cases, to foretell, with a greater or lesser degree of preci ON HYBRIDIZATION. 191 sion, the characters which may be expected to make their appearance in a new hybrid. The theory of mutation assumes that the quali- ties of a plant are not the expressions of a single, so-called “ specific character,” but depend on dif- ferent units. These units are more or less inde- pendent of one another, and may be combined in different ways. ‘Two or more allied species might consist of absolutely the same characters, but in different combinations. According to this view the progress in living nature has been by steps. Each step contributes a new character to those already existing, adding one unit more to the stock. It is evident that of all the species of a genus, the nearest ally of any given one is that from which it has taken its origin. . This origin is assumed to have taken place by shocks or leaps; or if the idea of a leap should confer the notion of too great a difference, one might use the expression, “by steps.” In horticulture such steps are often called sports ; but the meaning of this word comprises so many notions, and is so often limited to bud-sports, which mostly are of another nature, that I prefer to avoid it. Each leap or step signifies the acquisition of a single new character; and elementary species must therefore differ -from their nearest allies only in the possession of a single one. As a mat- ter of fact, the difference between the species of 192 RECENT OPINIONS. one genus are often not only greater, but even very much greater. But this is accounted for by the extinction of a greater or lesser number of forms, which no doubt is and has been of very general occurrence and must of course break up the continuity in the series of the remaining types. In such groups as Draba verna, Helianthemum vul- gare, Viola tricolor, the hieraciums, roses, bram- bles, and many other so-called younger genera and species, the single forms are so nearly allied that it is very difficult or perhaps even impossible to distinguish them from one another. These are the types of the original arrangement which is to be assumed for all groups consisting at present of more widely different forms, and, as is com- monly said, now showing “gaps.” Such small steps are called mutations, and more particularly progressive mutations, because they contribute to the evolution of the group. Once obtained, a new character may remain constant for centuries, and the new species will show no progress till a further mutation takes place and changes it again into a new specific form. The whole evolution goes on by such steps, the peri- ods between the successive bounds showing no signs of progress, but leaving the species un- changed. In this way it is clear that constancy of species and mutual descendance are in perfect harmony with one another. ON HYBRIDIZATION. 193 Besides the progressive mutations, there are other changes which are of minor value for the evolution in general, but of more general interest to horticulture. First of all, a character, once obtained, may be visible in the plant or it may become invisible, inactive, or as it is ordinarily called, dormant or latent. For instance, the blue and red colors of many flowers may disappear and thereby give rise to the white-flowered varieties. The visible quality is lost in such cases, but the corresponding internal one is not really lost, but has only become inactive or sleeping. That this is the case is seen in the frequent reversions in general, and particularly in the numerous instances of reversion by bud-variation as shown by varie- gated trees and shrubs, and by quite a host of garden varieties of evergreens (e.g. Cephalotarus pedunculata var. fastigiata, Cryptomeria Japonica var. spiraliter falcata, etc.). If now we compare a species with its mother- species, and a variety with its species, we readily see the difference. In both cases the difference in the description is caused by but a single character. But in the first case the internal character of the germ is present in the one and wanting in the other, whilst in the second case it is present in both and only different as to the degree of its activity, being active in the one and latent in the other. 194 RECENT OPINIONS. From this comparison we at once see that the behavior of two plants, when sexually united with one another, must differ principally in the two instances above mentioned. All other characters are assumed to be the same in both parents, and their union must follow the common rule of fer- tilization. But we must expect to get a different hybrid if the diagnostic character present in the elder one of the two forms is wanting in the younger one or is present but inactive. The active and the latent character may be simply in- terchanged, but in the case of a progressive mu- tation an exchange of characters is of course impossible. Activity and latency are not the sole degrees of development of acharacter. Nor is the difference between two forms, used for a crossing, ordinarily limited to a single point. But for the sake of clearness it seems better first to discuss these more simple cases and to put off the more complicated ones till after having elucidated the former. The becoming dormant of a character is one of the most ordinary types of the production of varie- ties. It is to be regarded as a mutation, since it is known in horticulture to come about by leaps and bounds. In the outer features it sets back the evolution as much as it had been brought for- ward by the progressive mutation by which the character in question was first obtained. For. ON HYBRIDIZATION. 195 this reason the seeming loss may be called a retro- gressive mutation. Limiting ourselves provisionally to these two types of differences between the two plants chosen for a crossing experiment, we will, for brevity’s sake, call “species” two forms of which the one has been derived from the other by a progressive mutation, and “ variety,’ the form derived from another in the way of retrogressive mutation. In this way we come to a very simple statement of the internal phenomena of crosses in general. For, in the first case, one parent has a character which is lacking in the other, and no exchange is possible. In the second case, both parents bear the same character, active in one, dormant in the other, and here they may therefore simply be ex- changed. This exchange is governed by the laws of proba- bility and depends, as far as we know, on no other principle or general laws. ‘The application of the laws of probability to this process was first dis- covered by Mendel, and the laws of exchange of characters in hybrids are now generally known as the laws of Mendel. They are limited to the crossing of varieties. If no exchange is possible because the differ- ential character is wholly wanting in the other parent, we may call the union “unisexual,” as was first proposed by Macfarlane. The extant features 196 RECENT OPINIONS. are then handed down to the hybrid offspring, but in a reduced state. Ordinarily they are reduced to one-half, as Macfarlane has pointed out ; but this is only a mean, around which the single cases seem to be grouped in the ordinary manner, most of them more or less strictly observing the rule, others differing in varying degrees. In extreme cases such variation can go so far as to repeat the character in question in the hybrid, or, on the other hand, to cause it to be wholly wanting. Hybrids from such unisexual crosses are ordinarily constant in their progeny, repeating in each successive gener- ation the characters of the first one. Such races do not obviously differ from true species, and Kerner has shown that in many cases wild species may owe their origin to such a cross. But instances are as yet rare, because, ordinarily, the two plants chosen for a cross differ in more than one point, and even mostly differ partly in specific characters, and partly in such as have been obtained by retro- gressive mutations. Hybrids of varieties follow Mendel’s laws, as we have said. ‘Two essential points are here to be distinguished, viz., the character invisible in the hybrid itself, and the behavior of the two opposite qualities in their progeny. We will first consider the hybrids themselves. According to the limits chosen above for our present discussion, the hybrid inherits from one ON HYBRIDIZATION. 197 parent a character in an active condition, and from the other the same character in a dormant state. From this method of viewing their constitution, it is evidently to be expected that the differential character will be active in the hybrid too, perhaps aided but perhaps also more or less hindered in its expression by the dormant counterpart. The evi- dence afforded by the experiments of Mendel, Correns, Tschermak, Webber, and myself shows that the differential character is really active in the hybrids, and that the weakening by its dormant opponent is ordinarily very slight, often wholly wanting, and only occasionally reducing it to nearly one-half. (Hyoscyamus pallidus x niger.) ‘This rule is commonly expressed by saying that the phylogenetically older character, z.e. that of the species, is dominant or prevailing over the antago- nistic character of the younger parent or the va- riety. It is the first of Mendel’s laws, but here expressed in terms, not of Mendel, but proper to the mutation theory. The second of Mendel’s laws governs the split- ting up of the character in the offspring of the hybrids. Mendel assumes that at the time of the production of the sexual cells the two antagonistic qualities, combined in the hybrid, separate and leave each other, the dominant coming into one- half of the male and female elements, and the opposite or recessive coming into the other half. 198 RECENT OPINIONS. If now, in the act of fertilization, the male and female cells are combined simply according to the laws of probability, each cell has an equal chance to unite with a cell bearing the same or with a cell bearing the opposite character. This leads to four combinations of equal frequency, a male dominant combining with a dominant or a reces- sive female, and a male recessive uniting in the same way with a dominant or a recessive female. Or, having no regard to the sex, we have dominant x dominant, recessive x recessive, and two cases of dominant x recessive. The offspring of hybrids consists, therefore, of three different groups of individuals. One of them bears only the active character, one of them only the latent, and the other group, containing the double number of specimens of each of the two. first, consists of new hybrids. The first group will have the character of one grandparent, the second that of the other, the third that of the parents or hybrids of the first generation. The two first divisions will be constant like the original parent- species; the last one must split up in the same way as the original hybrids themselves. No new form is obtained by such a crossing, as no new com- bination of qualities was possible. The hybrids obtained are called monohybrids, because the parents differ only in a single point. They are evidently of no practical interest, but it is equally ON HYBRIDIZATION. 199 evident that they give us the key to the explana- tion of the phenomena exhibited in the more com- plex cases; for, as a rule, these obey the same laws as the monohybrids with respect to the different distinguishing characters, whilst these are them- selves combined according to the ordinary laws of probability. If we sexually combine two forms, which differ in two points, the hybrids are called dihybrids; if the difference extends to three or more characters, they bear the names of tripolyhybrids. The most important result of the study of such cases is, that the different characters of the parents may be united by crossing and give rise to hybrids, of which some are constant in their progeny and others not. The last ones split up according to the same rules as do the monohybrids, and are only of theoretical interest or at best are the means of obtaining the constant races in an easier, though slower, way than by getting them directly. On the other hand, the constant races are of the highest value, as well in horticultural as in agricultural practice. As many combinations as are to be ex- pected really appear as constant races. If the crossed varieties differ in two characters, two new combinations are possible and obtained. For instance, by crossing the blue and thorny thorn- apple with the white-flowered thornless variety, one obtains blue thornless and white thorny forms, 200 RECENT OPINIONS. each of which gives a constant race. In the case of three differential characters, eight combinations are possible, two of them are equal to the parents, and so we will expect six new races, as, for instance, in the cases of wheat and oats studied by Rimpau (cf. “ Mutationstheorie,” II., p. 192). The prac- tical horticulturists and agriculturists will have to choose from these new races the best ones for further cultivation, but the numerical laws of Mendel will enable them to calculate beforehand what they have to expect and in which way they have to direct their selections. The laws of Mendel are not only valid for the cases of retrogressive variations, they also may be applied to all other cases, in which the differential character is internally present in both parents of a cross, but in different conditions. The prin- cipal conditions are the active and the dormant ones, constituting, as we have seen, the species and the constant variety. But there are other conditions of which we have here to name only the semi-active one. This is the internal charac- ter of those extremely variable forms which are so highly esteemed in horticulture, as double flowers, variegated leaves, and soon. Crossed with the true species, they comply with Mendel’s laws, and the results of the crossings, therefore, may be calculated beforehand. But their high degree of variability is inherited by the hybrids and makes it often very ON HYBRIDIZATION. 201 difficult as well to prove this compliance as to make use of it in practice. Coming now to even more complicated cases, we have to treat of those in which some characters differ progressively or unisexually and others in the retrogressive or in the digressive way. Or, in other terms, we have to inquire into the cross- ings in which the parents differ at once in specific and in varietal or racial marks. It will be readily seen that this case, though very complicated from an analytical point of view, is in practice the ordi- nary one. Pure unisexual or pure Mendel crosses are very rare, and seldom of great importance. Nearly all interesting horticultural crossings bear the mixed character we now have to speak of. The mutation-theory of course assumes the recip- rocal independence of the single characters for this case also. The unisexual differences must follow the laws studied by Macfarlane, the antago- nistic qualities those pointed out by Mendel. In regard to the first, the hybrids will therefore be in some degree intermediate between the parents, and constant in their progeny. In regard to the last, they will bear the dominant characters, and split up in their children, giving as many new constant strains as new combinations of these characters are possible. It is evident that the applications of the laws above mentioned may in this manner lead to the 202 RECENT OPINIONS. calculating beforehand of the results of all pro- jected crosses. But the researches are as yet only in their prime, and the true distinction of the units of the characters, which has to be the base of all such calculations, demands malts previous experimental work. The discussions given above concern only spe- cies and varieties in the ordinary immutable state. When mutable, the conditions of the in- ternal characters are of course totally different, and neither the laws of the unisexual crossings nor those of Mendel are applicable. (See De Vries’s paper “On Crosses with Dissimilar Heredity.”) III. THe FoRwARD MOVEMENT IN PLANT- BREEDING.! The first specific interest in cultivated plants was in the gross kinds or species. As the con- tact with plants became more intimate, various in- definite form-groups were recognized within the limits of the species. Gradually, with the intensi- fying of domestication and cultivation, very par- ticular groups appeared and were recognized. These smaller groups came finally to be designated 1 Read April 2, 1903, before the American Philosophical Society, and reprinted, with minor alterations, from proceed- ings of the society, Vol. XLII. No. 172. THE FORWARD MOVEMENT. 203 by names, and the idea of the definite and homo- geneous cultural variety came into existence. The variety-conception is really a late one in the development of the human race. It is practically only within the past two centuries that cultivated varieties of plants have been recognized as be- ing worthy of receiving designative names. It is within this period, also, that most of the great breeds of animals have been defined and separately named. All this measures the increasing intimacy of our contact with domesticated plants and animals. It is a record of our progress. The peoples that are most advanced in the cultivation of any plant are the ones that have the most named varieties of that plant. In Japan, to this day, the plums are said to pass under ill-defined class names. We have introduced these classes, have sorted out the particular forms that promise to be of value to us, and have given them specific American names. Not long ago a native professor in Japan wrote me asking for cions of these plums, in order that he might introduce Japanese plums into Japan. The Russian apples are designated to some extent by class-names; in fact, it was not until the ap- pearance of Regel’s work, about a generation ago, that Russian pomology may be said to have been born. What constitutes a variety is increasingly more difficult to define, because we are constantly 204 RECENT OPINIONS. differentiating on smaller points. The growth of the variety-conception is really the growth of the power of analysis. The earlier recognized varieties seem to have come into existence unchallenged. There is very little record of inquiry as to how or why or even where they originated. That is, the quest of the origin arose long after the recognition of the va- riety as a variety. Even after inquisitive search into origins had begun there was little effort to produce these varieties. The describing of va- rieties and the search into their histories was a special work of the nineteenth century. One has | only to consult such American works as Downing’s “Fruits and Fruit Trees of America,” and Burr’s “Field and Garden Vegetables of America,” to see how carefully and methodically the descriptions and synonymy of the varieties were worked out. These are types of excellent pieces of editorial and ~ formal systematic work. There have been isolated efforts at producing varieties for many years. These efforts began be- fore the time of the general discussion of organic evolution. In fact, it was on such experiments that Darwin drew heavily in some of his most im- portant writing. Roughly speaking, however, the conception that the kinds of plants can be definitely modified and varied by man is a product of the last half century. We now believe that there is such THE FORWARD MOVEMENT. 205 a possibility as plant-breeding. It is really a more modern conception, so far as its general acceptance is concerned, than animal-breeding. But both animal-breeding and plant-breeding are the results of a new attitude toward the forms of life —a con- viction that the very structure, habits, and attri- butes are amenable to change and control by man. This is really one of the great new attitudes of the modern world. Formerly, and even up to the present time, the variety has been taken as the unit for plant-breed- ing work, as it has been for descriptive and classi- ficatory work. Whether we believed it or not, we have accepted it as a fairly definite thing or entity. Yet, what isa variety? Only the ideal of one man oraset of men. Custom may define its boundaries, but in fact it has no boundaries. At best, a variety is only an assemblage of forms that agree rather more than they differ; and any one of these forms may, with equal propriety, be called another va- riety. Shall we continue to consider the variety as a unit or basis from which we are to breed for the purpose of producing other varieties? Or shall we still further refine our ideals, and find that the variety-conception is really only a mark of an im- perfect and superficial expression of an immature age? Now, plant-breeding is worthy of the name only as it sets definite ideals and is able to attain them. 206 — RECENT OPINIONS. Merely to produce new things is of no merit: that was done long before man was evolved. A child can “produce” a new variety, but it may learn nothing and contribute nothing in producing it. I have myself produced fifteen hundred new kinds of pumpkins and squashes, but I had no idea what I was to produce, the world is no better for my having produced them, and I am no wiser (except in experience) than I was before. In many “new” things that are produced there may be dispute as to whether they are new, and as to whether they are distinct enough to be named and therefore to be ranked as varieties at all. This is not science, nor even breeding: it is playing and guessing. What does the world care whether John Jones produces “Jones’s Giant Beardless Wheat”? But it does care if he produces a wheat having a half of one per cent more protein. We must give up the production of mere “varieties” ; _ we must breed for certain definite attributes that will make the new generations of plants more efficient for certain purposes: this is the new out- look in plant-breeding. Happily, we are not without abundant accom- plishment in this new field. The last ten years has seen a remarkable specialization in the pro- ducing of plants that are adapted to particular needs. The days of merely crossing and sowing the seeds to see what will turn up are already past THE FORWARD MOVEMENT. 207 with those who are engaged seriously in the work. The old method was hit-and-miss, and the result was to take what good luck put in our way: the new method proceeds definitely and directly, and the result is the necessary outcome of the line of effort. The crux of the new ideal is efficiency in one particular attribute in the product of the breeding. These attributes are measurable; the kind of results are foreseen in the plan, or are predictable. All these remarks are typically illustrated in many investigations now making in the experi- ment stations. As an example, I will describe the experiments with corn-breeding now conducting in Illinois. It is significant to note what are the reasons for breeding new corns, as stated by Pro- fessor Hopkins in Bulletin 82 of the Lllinois Ex- periment Station. “In its own publication a large commercial concern, which uses enormous quantities of corn, makes the following statements : — “¢ A bushel of ordinary corn, weighing fifty-six pounds, contains about four and one-half pounds of germ, thirty-six pounds of dry starch, seven | pounds of gluten, and five pounds of bran or hull, the balance in weight being made up of water, soluble matter, etc. The value of the germ lies in the fact that it contains over forty per cent of corn oil, worth, say, five cents per pound, while the 208 RECENT OPINIONS. starch is worth one and one-half cents, the gluten one cent, and the hull about one-half cent per pound. ) «Tt can readily be seen that a variety of corn containing, say, one pound more oil per bushel would be in large demand. “Farmers throughout the country do well to communicate with their respective agricultural experiment stations and secure their codperation along these lines.’ “These are statements and suggestions which should, and do, attract the attention of experiment station men. They are made by the Glucose Sugar Refining Company of Chicago, a company which purchases and uses, in its six factories, about fifty million bushels of corn annually. Ac- cording to these statements, if the oil of corn could be increased one pound per bushel, the actual value of the corn for glucose factories would be increased five cents per bushel; and the president of the Glucose Sugar Refining Company - has personally assured the writer that his company would be glad to pay a higher price for high oil corn whenever it can be furnished in large quanti-_ ties. The increase of five cents per bushel on fifty million bushels would add $2,500,000 to the value of the corn purchased by this one company each year. ‘The glucose factories are now extract- ing the oil from all the corn they use and are THE FORWARD MOVEMENT. 209 unable to supply the market demand for corn oil. On the other hand, to these manufacturers protein is a cheap by-product, and consequently they want less protein in corn. “Corn with a lower oil content is desired as a feed for bacon hogs, especially for our export trade, very extensive and thorough investigations conducted in Germany and Canada having proved conclusively that ordinary corn contains too much oil for the production of the hard, firm bacon which is demanded in the markets of Great Britain and Continental Europe.” It is very interesting to note that this does not mention the improvement of Leaming’s White, or Jones’s Yellow Dent, or any other named variety of corn, nor does it propose that any new variety shall be created. It suggests what may be done with any variety of corn. The experiments in Illinois demonstrate that “the yield of corn can be increased, and the chemical composition of the kernel can be changed as may be desired, either to increase or decrease the protein, the oil, or the starch.” The breeding of the corn, in the Illinois experi- ments, proceeds along two general lines, —for physical perfection and for chemical perfection. Selection for physical merit proceeds as follows, to quote again from Professor Hopkins: “ The most perfect ears obtainable of the variety of corn P 210 RECENT OPINIONS. which it is desired to breed should be selected. These ears should conform to the desirable stand- ards of this variety, and should possess the prin- cipal properties which belong to perfect ears of corn, so far as they are known and as completely as it is possible to secure them. These physical characteristics and properties include the length, circumference, and shape of the ear and of the cob; the number of rows of kernels and the num- ber of kernels in the row; the weight and color of the grain and of the cob; and the size and shape of the kernels. In making this selection the breeder may have in his mind a perfect ear of corn and make the physical selection of seed ears by simple inspection, or he may make absolute counts and measurements and reduce the physi- cal selection almost to an exact or mathematical basis.” The selection for chemical content is made on two bases, —on the general gross structure of the corn kernel as determined by “ mechanical examination,” and on chemical analysis of the kernel. Chemical examination by means of mechanical examina- tion is as follows: “ The selection of seed ears for improved chemical composition by mechanical examination of the kernels is not only of much assistance to the chemist in enabling him to reduce greatly the chemical work involved in seed-corn selection, but it is of the greatest practical value to the ordinary seed-corn grower who is trying to improve his seed corn with very limited service, if any, from the analytical chemist. This chemical selection of seed ears THE FORWARD MOVEMENT. Ate by mechanical examination, as well as by chemical analysis (which is described below), is based upon two facts : — “J. That the ear of corn is approximately uniform throughout in the chemical composition of its kernels. «2. That there is a wide variation in the chemical com- position of different ears, even of the same variety of corn. These two facts are well illustrated in the table : — PROTEIN IN SINGLE KERNELS. Ear A, | Ear B, | EarC, | Ear D, PROTEIN,| PROTEIN,| PROTEIN,| PROTEIN, PER PER PER PER CENT. CENT. CENT. CENT. Kernel No.1. . é 12.46 11.53 7.45 8.72 Kernel No. 2 . 12.54 12.32 7.54 8.41 Kernel No. 3 12.44 12.19 7.69 8.73 Kernel No. 4 12.50 12.54 7.47 8.31 Kernel No. 5 12.30 12.14 7.74 8.02 Kernel No. 6 12.49 12.95 8.70 8.76 Kernel No. 7 12.50 12.84 8.46 8.89 Kernel No. 8 12.14 — 8.69 9.02 Kernel No. 9 12.14 12.04 8.86 8.96 Kernel No. 10 12.71 12.75 8.10 8.89 “Tt will be observed that while there are, of course, small differences among the different kernels of the same ear, yet each ear has an individuality as a whole, the difference in composition between different ears being much more marked than between different kernels of the same ear. “ The uniformity of the individual ear makes it possible to estimate or to determine the composition of the corn by the examination or analysis of a few kernels. The re- mainder of the kernels on the ear may then be planted if desired. The wide variation in the composition between 912 RECENT OPINIONS. different ears furnishes a starting-point for the selection of seed in any of the several different lines of desired improve- ment. “The method of making a chemical selection of ears of seed corn by a simple mechanical examination of the kernels is based upon the fact that the kernel of corn is not homogeneous in structure, but consists of several dis- tinct and readily observable parts of markedly different chemical composition. Aside from the hull which sur- rounds the kernel there are three principal parts in a grain of corn : — “1. The darker colored and rather hard and horny layer lying next to the hull, principally in the edges and toward the tip end of the kernel, where it is about three millimetres, or one-eighth of an inch in thickness. “2. The white, starchy-appearing part occupying the crown end of the kernel and usually also immediately sur- rounding, or partially surrounding, the germ. “3. The germ itself, which occupies the central part of the kernel toward the tip end. “These different parts of the corn kernel can be readily recognized by merely dissecting a single kernel with a pocket-knife, and it may be added that this is the only instrument needed by anybody in making a chemical selec- tion of seed corn by mechanical examination. “The horny layer, which usually constitutes about sixty- five per cent of the corn kernel, contains a large proportion of the total protein in the kernel. “The white, starchy part constitutes about twenty per cent of the whole kernel, and contains a small proportion of the total protein. The germ constitutes only about ten per cent of the corn kernel; but while it is rich in protein, it also contains more than eighty-five per cent of the total oil content of the whole kernel, the remainder of the a _— distributed in all of the other parts. THE FORWARD MOVEMENT. 213 “By keeping in mind that the horny layer is large in proportion, and also quite rich in protein, and that the germ, although rather small in proportion, is very rich in protein, so that these two parts contain a very large propor- tion of the total protein in the corn kernel, it will be readily seen that by selecting ears whose kernels contain more than the average proportion of germ and horny layer, we are really selecting ears which are above the average in their protein content. As a matter of fact, the method is even more simple than this, because the white, starchy part is approximately the complement of, and varies inversely as, the sum of the other constituents; and to pick out seed corn of high protein content it is only necessary to select those ears whose kernels show a relatively small proportion of the white, starchy part surrounding the germ. “As more than eighty-five per cent of the oil in the kernel is contained in the germ, it follows that ears of corn are relatively high or low in their oil content, according as their kernels have a larger or smaller proportion of germ. “In selecting seed corn by chemical analysis, we remove from the individual ear two adjacent rows of kernels as a representative sample. This sample is ground and analyzed as completely as may be necessary to enable us to decide whether the ear is suitable for seed for the particular kind of corn which it is desired to breed. Dry matter is always determined in order to reduce all other determinations to the strictly uniform and comparable water-free basis. If, for example, we desire to change only the protein content, then protein is determined. If we are breeding to change both the protein and the oil, then determinations of both of these con tituents must be made.” Any careful farmer can make such examinations as these. The relative abundance of one or the 214 RECENT OPINIONS. other of three areas in the kernel will indicate what ears should be chosen for seed. Professor Hopkins proposes a system of field trials in which one ear furnishes plants for one row, thereby allow- ing the operator to see and measure the individu- ality of eachear. By choosing ears that most nearly approach the ideal, and then by continued selec- tion, the desired result is to be secured. It is impossible to overestimate the value of any concerted corn-breeding work of this general type. The grain alone of the corn crop is worth about one billion dollars annually. It is no doubt pos- sible greatly to increase this efficiency. An interesting cognate inquiry to this direct breeding work is the study of the commercial grades of grains. It is a most singular fact that the dealer’s “grades” are of a very different kind from the farmer’s “ varieties.” In the great mar- kets, for example, corn is sold as “ No. 1 Yellow,” “No. 2 Yellow,” “No. 3 Yellow.” Any yellow corn may be thrown into these grades. What constitutes a grade is essentially a judgment on the part of every dealer. There is, therefore, a very natural tendency on the part of dealers to deliver grain as near the bottom of the grade line as an inspector will pass, and consequently there is a marked deterioration as the grain reaches the seaboard. The result is that the grain is likely to be condemned or criticised when it reaches Liv- THE FORWARD MOVEMENT. 215 erpool. Complaints having come to the govern- ment, the United States Department of Agriculture has undertaken to determine how far the grades of grain can be reduced to indisputable instrumental measurement. This work is now in the hands of C. 8. Scofield, in the Bureau of Plant Industry. The result is likely to be a closer defining of what a grade is; and this point once determined, the producer will make an effort to grow such grain as will grade to No. 1, and thereby reach the extra price. Eventually the efficiency points of the grower and the commercial grades of the dealer ought nearly or quite to coincide. There should come a time when corn is sold on its inherent merits, as, for example, on its starch content. This corn would not then be graded 1, 2, and 3 on its starch content, because that content would be as- sured in the entire product; but the Grade 1 would mean prime physical condition, and the lower grades inferior physical condition. Eventually something like varietal names may be attached to those kinds of corns that, for example, grade fifteen per cent protein. The name would be a guarantee of the approximate content, as it now is in a commercial fertilizer. Closely allied to the corn-breeding Sank of [lli- nois (which is carried on by the Experiment Station and also by a commercial firm) is the wheat-breed- ing and flax-breeding work in Minnesota under 216 RECENT OPINIONS. the direction of Professor Hays. Mr. Hays’s aim has been chiefly to increase general value per acre. The following sketch is made from his notes : — Examples are given of increased efficiency in varieties produced at the Minnesota Experiment Station in coopera- tion with the U.S. Bureau of Plant Industry and other stations. Minn. No. 163 wheat was bred by selection from Fife parentage. During three years’ comparison in field tests at University Farm, near Minneapolis, it averaged 2.7 bushels gain per acre, or eleven per cent better than its parent variety, as shown by the following table: — Minn. No. 163 . ‘ ; : . : ‘ ‘ . 28.5 bushels Fife parent , ‘ . . . ° ° . « Da ae Increase . , : : . ° = " « 25 ae In 1899, this wheat was sold to one hundred farmers, thirty-eight of whom made the comparison between this and their common wheats in a manner fair to both. The follow- ing table shows the average increased yield to have been 1.4 bushels per acre, or eight per cent :— Minn. No. 163, average yield . : : : ° . 18.1 bushels Common wheats, average yield . ‘ ° - 6.7 = Increase . A : ‘ : : ° : c. fees In 1903, this wheat grew on at least 100,000 acres, and since it was first distributed it has produced $100,000 more than would have resulted from the varieties that it has displaced. Minn. No. 169 wheat was bred by selection from a Blue Stem foundation. During the first four years it was in our field tests it averaged 4.9 bushels more than the parent wheat, as displayed by the following table of average yields, showing an increase over its parent variety of twenty per cent : — THE FORWARD MOVEMENT. vA hig Minn. No. 169 . : 5 J A < 5 : . 28.5 bushels Minn. No. 51 . 5 3 F : . . oO ¥e Gain . , ‘ . ‘ : ‘ - A Bere’ 8 OP Rae: In 1902, this wheat was sent in four-bushel lots, at $1.50 - per bushel, to three hundred and seventy-five farmers. Eighty-nine reports gave comparisons that were fair both to the new and old wheats, and there were obtained the fol- lowing average yields, showing an increase over the common wheats for the entire State of eighteen per cent :— Minn. No. 169 . é - 3 ‘ ° P F . 21.5 bushels Common wheats 3 . ; ‘ 5 ‘ s 182 om Increase. - : E : E - s ee ier ee In 1903, more than 150,000 bushels of this wheat were grown, most of which will be used for seed in 1904. Similar results have been secured with flax. Seven years ago, Professor Hays chose seven samples of the common Minnesota and Dakota flax, and made by selection many new types for the production of seed, and numerous other types, especially for production of fibre. The following table gives the general results for 1902 :— Yield of Yieldof Heightin grain. straw. inches. Av. of 4 best varieties selected for seed . 17.8 1.40 23 Av. of 4 best varieties selected for fibre . 10.5 Lac 35 Av. of 4 best common varieties (from outside sources) . : : : . 11.9 1.52 24 Increase . ‘ ; é : x BY 24 In field trials, in 1902, the increased yield of flax per acre of the new varieties bred for seed was forty-nine per cent; and the increased height of the new varieties bred for fibre was forty-six per cent more than the common flax. 218 RECENT OPINIONS. “We have developed statistical methods,” Pro- fessor Hays writes, “of dealing with such plants as wheat, alfalfa, corn, and, in fact, nearly all of the field crops where it is necessary or very advan- tageous to plant a single seed in a hill, that selec- tions may be made and the breeding powers of parent plants measured. The general features of this statistical work may be stated as follows: ~ Every acquisition or newly bred variety receives a number written thus, ‘Minn. No. 13 corn,’ for example. It is also botanically described and the facts concerning its history, name, description, etc., entered in our ‘ Minnesota Number Book.’ If the newly secured variety is an exceptionally promising one, it is put into field tests, but ordinarily in the preliminary garden test the first year. Promis- ing acquisitions and promising newly bred hybrid stocks are entered in the nursery, where their breeding by rigid selection is begun, and large numbers of plants are grown, one in each hill, giving each plant the same space and opportunities as each other plant. By processes of elimination, the few best performers are secured. The next year we plant a large number of the progeny of each of these superior mother-plants. The aver- age yield, height, and other measures are taken of the progeny of each mother-plant. The breeding value of each mother-plant is thus secured in terms of the average performance of the progeny ; THE FORWARD MOVEMENT. 219 these are better measures of breeding power than are the measures of mere performance of the indi- vidual. These tests of the breeding values of the mother-plants are continued two and sometimes three years. Seeds from parent plants producing the best average progeny are used alone or in mixtures of close-pollinated species, and in mix- tures in open pollinated species as the foundation of new varieties. These are tested in the field with the parent and other best standard varieties for three years. Any introduced or newly bred variety which is an especially good yielder of value per acre is sent to the codperating State Experi- ment Stations in surrounding States and to our substations, and its quantity is rapidly increased. Any variety that is specially promising after being tried for, say, two years at several stations, is in- creased to sufficient quantity to sell to a number of farmers in each county in the State. This seed, backed by all the force of pedigree that we can command, is sold at a high price, so as to make the seed business profitable, and men are induced to raise it and sell large quantities at a price which will yield them a profit.” A most gratifying augury of the coming type of effort is to be found in the work of the Plant- Breeding Laboratory of the national Department of Agriculture. This is an organization effected for the purpose of producing types or kinds of 220 RECENT OPINIONS. plants that shall meet particular requirements. Its work is now proceeding with many groups of plants, but the burden of all its effort is efficiency in the final product. Its work with cotton promises to do nothing less than to revolutionize the cotton industry. The special difficulty with the present Upland cotton is the shortness of the “staple” or fibre. This inch-long staple sells at present (1908) for eight to eight and one-quarter cents a pound, whereas the long staple of the Sea Island cotton sells for twenty-five to thirty cents per pound. The effort is to secure a longer staple for the Upland, either by crossing it with the Sea Island or by working with some foreign long-staple type. The Egyptian cotton has a long staple, and this is now being used as one of the foundation stocks. But the Egyptian cotton possesses faults along with its long staple. It will be the work of years, by means of careful selection, to augment or main- tain the desirable qualities and to eliminate the un- desirable qualities; when this is done, the cotton will no longer be the Egyptian, but practically a new creation, and this new creation should receive a new name in order to distinguish it from the inferior Egyptian from which it will have had its birth. Under the leadership of Mr. Webber, this new plant-breeding enterprise (prob- ably the largest in the world) is now extended to citrous fruits, apples, pineapples, oats, tobaccos, THE FORWARD MOVEMENT. at. and other crops; and there is every indication that its usefulness will expand greatly within the immediate future. Other institutions, and other divisions of the Department of Agricul- ture, are conducting similar work. In fact, one or more officers at nearly every experiment station are now giving attention to some phase of plant- breeding work. It is significant that effort is now being given to the improvement of the staple farm crops, whereas a few years ago plant-breed- ing work was supposed to belong mostly to the horticulturist. Time is now on when every re- sourceful farmer must look to the improving of the intrinsic merits of his crops. The modern methods of plant-breeding demand, first, that the breeder shall familiarize himself thoroughly with the characteristics of the group of plants with which he is to work. He must have very specific and definite knowledge of what makes the plant valuable and what its shortcomings are.— Then he must secure as starting-points plants that give promise in the desired direction. Thereafter his skill will be taxed in selecting along responsive lines, in making accurate and significant statistical measures, in devising workable systems of testing. He must grow large numbers of plants, if he is working with farm crops, in order to multiply his chances of securing desirable variations and to minimize the errors. 992 RECENT OPINIONS. A promising course of breeding is one that shall develop disease-resisting races within the variety. Considerable progress has already been made in this direction with cotton, oats, and some other crops. Now and then a hill or a row or a variety of potato resists the blight. Why? May it not be used as a starting-point for the development of a blight-resistant strain? The producing of disease- resisting and pest-resisting races is one of the most promising lines of work in the new plant pathology. : Nor are all these advances to be secured from seed selection alone. The cuttings and grafts of fruit plants perpetuate the parental characteristics with a good degree of surety. The time must soon come when it will not be sufficient to multiply the Bartlett pear from the Bartlett pear. We shall still further specialize our ideals and propagate _ from particular Bartlett pear trees that have made record performances. This subject is being tested in New York and elsewhere. It is one of the most important problems now before the nurseryman and orchardist.! All this plant-breeding work is especially of a kind to demand governmental support. The prog- 1 See, for example, a discussion of this subject in a paper on ‘*The Whole Question of Varieties,’ in the Report of the American Association of Nurserymen, 1903 (Detroit conven- tion). The subject is also discussed in ‘‘ Survival of the Unlike.”’ THE FORWARD MOVEMENT. 223 ress of invention can be left to private initiative, because the person can patent his device and secure all the financial returns that itis worth. A variety cannot well be patented or controlled. This is par- ticularly true of these great race improvements, in which no distinct and namable variety results ; and these race improvements are the very ones that are most likely to be of greatest benefit to agriculture and therefore to the nation. These methods and ideals may all be summed up as follows : — I. Determining on what the merit in any group of plants depends, and finding out what_is needed to make the plants more efficient. What makes a potato “mealy ” ? II. Securing a start in the desired direction by _ (a) Choosing for seed-bearing any plants that y are promising ; (6) Introducing prominent foundation stock from other regions or foreign countries ; (c) Crossing for the purpose of injecting a new or better character into the strain. III. Continued selecting, careful testing, and keeping accurate statistical measurements and records to maintain the progress true to line. The first thing that strikes one in all this new work is its strong contrast with the old ideals. The “points” of the plants are those of “ perform- ance” and “efficiency.” It brings into sharp relief 224- RECENT OPINIONS. the accustomed ideas as to what are the “good points” in any plant, illustrating the fact that these points are for the most part largely fanciful, are founded on a priort judgments, and are more often correlated with mere “looks” than with efficiency. An excellent example may be taken from corn. In “scaling” any variety of corn, it is customary to assume that the perfect ear is one nearly or quite uniformly cylindrical throughout its length and having the tip and butt well covered with kernels. In fact, the old idea of a good variety of corn is one that bears such ears. Now this ideal is clearly one of perfection and completeness of mere form. We have no knowledge that such form has definite correlation with productiveness, hardiness, drought-resisting qualities, protein, or starch content —and yet these attributes are the ones that make corn worth growing at all. Such ears may be more productive of kernels, but they may not be characteristic of plants that produce the greatest number of large ears. It may be dis- tinctly worth while to breed for this perfection in form, providing it is associated with breeding for efficiency. An illustration also may be taken from string beans. The ideal pod is considered to be one of which the tip projection is very short and only shghtly curved. ‘This apparently is a ques- tion of comeliness, although a short tip may be associated in the popular mind with the absence of THE FORWARD MOVEMENT. Pade: “string” in the pod; but we do not know how much this character is related to the efficiency of the bean pod. We are now undergoing much the same challenging of ideas respecting the “ points ” of animals. These “points,” by means of which the animals are “scored,” are often merely arbitrary. Now, animals and plants are bred to the ideals ex- pressed in these arbitrary points, by choosing for parents the individuals that score the highest. When it becomes necessary to recast our “scales of points,” the whole course of evolution of domes- tic plants and animals is likely to be changed. We are to breed not so much for merely new and striking characters that will enable us to name, describe, and sell a “novelty,” as to improve the performance along accustomed lines. We do not need new varieties of seedling potatoes so much as we need to improve, by means of selec- tion, some of the varieties that we already pos- sess. We are not to start with a variety, but witha plant. It is possible to secure a five per cent increase in the efficiency of our field crops; this would mean the annual addition of hundreds of millions of dollars to the national gain. The purpose, then, of our new plant-breeding is to produce plants that are more efficient for spe- cific uses and specific regions. They are to be specially adapted. ‘These efficiency omits are of six general categories : — Q 226 RECENT OPINIONS. Yield ideals. Quality ideals. Seasonal ideals. Physical conformation ideals. 5. Regional adaptation ideals—as to climate, altitude, soil. 6. Resistant ideals —as to diseases and insects. The main improvement and evolution of agri- culture are going to come as the result of greater and better crop yield and greater and better ani- mal production. It is not to come primarily from invention, good roads, rural telephone, legislation, discussion of economics. All these are merely aids. Increased crop and animal production are to come from two agencies: improvement in the 4 care that they receive; improvement in the plants and animals themselves. In other words, the new — agriculture is to be built upon the combined re- sults of better cultivation and better breeding. ae far as the new breeding is concerned, it is =< characterized by perfect definiteness of purpose )and effort, the stripping away of all arbitrary . and factitious standards, the absence of speculative theory, and the insistence upon the great fact that every plant and animal has individuality. pele rah ie tikes ® eer a & 4 af ks *: . oe = * Mendelism is maize. ‘The first crossing was made in 1900, Stowell Evergreen being pollinated by Indian Flour corn. The ear resulting from this cross (1900) presented in color and com- position the characteristics of Indian Flour corn. This ear was planted in 1901. Some plants were pollinated in 1901 with Stowell Evergreen (one of the resulting ears shown at left) and some with the hybrid itself (a resulting ear on the right). — PLANT-BREEDING, LABORATORY, UNITED STATES DEPARTMENT OF AGRICULTURE. Te ad Pa Oe > & af 9 Zz - ‘ . - “ » . - , { £ 7 A ed bs f oul ae ws rf ie b 3 eis: ” roe ‘4 den¥- - * a rey Pele eet eer Any 723 ATG Se. we, ‘Te ee el ae a F > on <-. yore bial oN aes s LECTURE V. CURRENT PLANT-BREEDING PRACTICE, [Contributed to the Fourth Edition, 1906. ] _ One of the “signs of the times” in North Amer- ica is the attention that is being given to the practi- cal breeding of plants. The academic discussion of the subject is now well past, and a host of per- sons is actually at work. Results are accumu- lating rapidly with very many kinds of plants ; but most breeders are too busy with their enter- taining work to stop long with philosophy or specu-~ lation. Eventually, of course, we shall be able to formulate somewhat definite statements as to how to proceed to secure desired results, and then the literature of plant-breeding can be intelligently rewritten. However, there is no hope that plant- breeding can ever proceed with such exactness as to enable us to produce forthwith the things that we desire, in the way in which the mechanician devises new machines, notwithstanding all the suggestions of persons who write with much self- assurance. For all that we can now see, plant- breeding will always be an experimental process. 227 228 CURRENT PLANT—BREEDING PRACTICE. It is this very experimental uncertainty of the work that gives it much of its charm to inquisitive and sensitive minds. In considering the American achievement in plant-breeding, we must divest ourselves at the outset of all idea of “*wonder,” and “ miracle,” and other nonsense, which has been so much written into the subject in very recent time. Plant- breeding is a plain and serious business, to be conducted by carefully trained persons in a pains- taking and methodical way. It is not magic. There are persons who have unusual native judg- ment as to the merits and capabilities of plants and who develop great manual skill; but they are plain and modest citizens, nevertheless, and their methods are perfectly normal and scrutable. The wonder-mongers are the reporters, not the plant- breeders. j It is a curious psychological phenomenon that the populace, or a certain part of it, seems to lose its head now and then. This phenomenon is not peculiar to politics. It enters those domains that are compassed by fact and that in ordinary times are dominated by common sense. Plant-breeding has been seized of this sensationalism. News- papers, magazines, and books have spread the most wonderful tales. The lay writers have at last awakened to the fact that great progress is making in agricultural subjects, and, with a frag- THE THREE ESSENTIALS. 229 mentary and superficial view here and there, have written of the subjects with all the enthusiasm and partiality of new discovery. I have now in mind not only the inflated writing about plant- breeding, which constitutes a regrettable contribu- tion to current horticultural literature, but also that general tendency to exploit everything that is capable of high coloring. I fear that the agri- cultural historian, when he takes account of the exploitations of the present day, will recall other stages in which we seem temporarily to have lost our better judgment, of which the Morus multicaulis craze and the lightning-rod boom are examples in two previous generations. Having now warned my reader that I have nothing marvellous in store, I shall proceed to indicate some of the ways in which American plant-breeders are working, fully conscious that. the space at my disposal is much too little to allow of any adequate presentation of the subject. It. may not be out of place to call the reader’s atten- tion to the three foundations on which rests the increased productiveness of crops and animals : — The enrichment of the land ; The tillage and care; The producing of better varieties and strains. We have long given careful attention to the first two; now we are studying the third with new enthusiasm and purpose. . There recently has been 230 CURRENT PLANT—BREEDING PRACTICE. organized an “ American Breeders’ Association,” of which three conventions have now been held. The proceedings of the first two meetings are published in one volume, and the list of members constitutes a breeders’ directory; this list contains seven hundred and fifteen names of plant-breeders and animal-breeders. In the classified ‘“ business directory” are the following numbers interested in different phases of plant-breeding: fruit and nursery stock, forty persons; seed corn, twenty- nine persons; farm seeds, twenty-four persons. This classified list is not at all complete. The per- sons that are interested in the breeding of flowers alone are probably more numerous than all of these. Local crop-breeders’ societies are also being organized. The “ Nebraska Corn Improvers’ As- sociation ”’ met recently at Lincoln, with the fol- lowing papers on the programme : — Breeding Cereals, Prof. C. A. Zavitz, Guelph, Ontario. Breeding Timothy, Dr. A. D. Hopkins, Washington, D.C. The Corn Plant as affected by Rate of Planting, E. G. Mont- gomery, Nebraska Experiment Station. Practical Corn Breeding on a Large Scale, J. Dwight Funk, Bloomington, Ill. Fundamental Requirements for Grain Breeding, Prof. M. A. Carleton, Washington, D.C. Breeding Drouth Resistant Crops, R. Gauss, Denver, Col. Value of Corn Pollen from Suckers vs. from Main Stalks, C. P. Hartley, Washington, D.C. Experiments in Wheat Breeding, Alvin Keyser, Nebraska Experiment Station. EXTENT OF PLANT—BREEDING. oat The most methodical plant-breeding is now being done by officers of the experiment stations in the United States and Canada, and by the United States Department of Agriculture. In most of the experiment stations there is one per- son interested in improving horticultural plants and another interested in field crops; as there is an experiment station in every state and territory and in the provinces of Canada, it will be seen that there are more than one hundred persons who, by their profession, are directly concerned in plant-breeding, aside from a number of persons in the Plant-breeding Laboratory of the United States Department of Agriculture who devote themselves exclusively to this work, and not count- ing many persons in other branches of the Depart- ment who devote more or less of their energies to such subjects. The work is extended, also, into the hands of various assistants in the dif- ferent institutions; so that it is probably no exag- geration to say that three hundred professional investigators are now giving attention, for a greater or less part of their time, to measures for improving American crop production by means of breeding. Aside from this, plant- breeding is now a subject for instruction in many of the agricultural colleges, and in this way the impulse is carried far and wide over the country. 932 CURRENT PLANT-—BREEDING PRACTICE. Long before these professional experimenters be- gan their work, however, patient and painstaking men had been breeding plants. ‘They were “ prac- tical”? men; that is to say, they bred varieties in order that they might sell the stock. Consider the number of named varieties, in the catalogues, of cabbages and tomatoes and dahlias and roses and strawberries: all these originated somewhere, and somebody named them and introduced them. To be sure, many of these varieties were discoy- ered amongst other plants, no one knowing how or why they came; but many of them, particularly in the roses and other florists’ plants, were care- fully bred; and even the fortuitous varieties were often improved and “fixed” by subsequent selec- tion. If one is to sell a novelty, he must name it./ | The tendency, therefore, was to produce a form’ distinct enough in general external characters to be easily distinguishable; that is, to produce “varieties.” The experiment station man, how-~ ever, is not pressed by the necessity of selling his product. Therefore he cares little for merely producing a new variety; he may think it more) important to improve some existing variety or to intensify some character that is not usable in gen- eral catalogue descriptions: in short, he seeks for efficiency and not for mere characters. This type of effort was explained in the third edition of this book, and the description will still be found in the STAGES IN PLANT—BREEDING. 938 pages between 203 and 226. One might write a book on the plant-breeders who gave us the good old varieties that we still prize, working quietly and obscurely long before the days when periodi- cals cared to discuss the subject or before men of science condescended to investigate it. The pro- duction of varieties in those days was regarded as a trade secret, and this in part accounts for the small knowledge that we have had of the subject. I well remember the air of mystery that attached to the subject when I first began to in- quire into it, and the great difficulty of securing any publishable data even when I wrote this book ten years ago; but now the field is open and free, many ardent young fellows are exploring it, and if I were to write again, I should be bewildered by the facts and instances that I should find. Before proceeding to the discussion of details, I may be allowed to remind the reader of the pro- cesses or stages in plant-breeding: — 1. To determine what attributes it is desirable to work for; 2. To secure a variation ; 8. To improve and concrete the variation, if — need be, by selection. It matters not whether the breeder is Darwinian or De Vriesian, the methods are practically the same. Even if varieties are mutants, as De Vries supposes, —forms small or great that originate 234 CURRENT PLANT—-BREEDING PRACTICE. full-fledged, — we may still need to practise selec- tions as between mutants; and if any varieties turn out to be amenable to further separation by means of selection, it only proves that these par- ticular forms are not mutants. If a form is so well marked and so valuable and so constant that it needs no selection, then the breeder may rejoice that his task is so easy, and he should have suffi- cient time and enthusiasm left to cause him to, desire to repeat the experience. Howbeit, if the plant-breeder’s realm lies with plants that he must propagate by means of seed, selection is usually the one essential to success. How the variations or differences are to be secured in the first place, — whether by change of soil or climate, hybridi- zation, or the less arduous method of merely watching for them if perchance they are in the mood to appear, —is a question to be settled each man for himself; and he will likely find that there is no royal road, and in consequence he will try all methods and keeps his eyes open in the bar- gain. The greater the number of plants on which he experiments, the greater will be the likelihood of securing useful variation, and the more freely can he select ; all recent experience enforces this fact. forms and to cause the stock to “ come true” to seed ; and he may also be able to intensify his <9 By selection he hopes to cut off the undesirable i J aa . < 2 - : HEREDITY IN AMARANTUS. oa0 characters at the same time. To “come true,” means that the particular. attribute or form becomes hereditable. Sometimes the form is he- reditable in the beginning. I happen to have photographs showing such an example. It is the case of two red-root pigweeds, Amarantus retro- Fic. A.— The big pigweed, after frost. flecus, that grew in such a jostle of weeds that they had to take on different size and shape in order to live. A fuller account of these two pigweeds can be found on pages 258 to 263 of “Survival of the Unlike”; it is now sufficient to say that one of them got headway above its neighbors and meas- ured thirty inches in spread and twenty-four inches 236 CURRENT PLANT—BREEDING PRACTICE. in height, and that the other had a spread of nine inches and a height of twelve inches. The frame- work of the larger plant is shown in Fig. A. Seeds from both plants, equally mature to all appear- ances, were carefully sown in pans in the green- house ; those from the smaller plant germinated poorly, as seen in Fig. B; and when the plants came into bloom, there was still a marked difference, as shown in Fig. C. I have no reason to doubt that these differences would have been again heredi- table to some degree had I sown the seed; but as I had not set out to produce an improved strain of pigweed, I did not carry the test farther. All this suggests a method of securing such a plant as you may want. The material for new types of plants may be (a) the varieties already in use, (6) species or varieties introduced from foreign parts, (¢) native plants not yet domesticated, (d) hybrids. In the introduction of foreign plants, the past few years have been fertile. These plants are introduced primarily for their intrinsic merits; but almost immediately they are established in the new coun- try, they begin to change or vary, and soon form the basis of new direct forms or of hybrids. These foreign plants are being brought in by commercial firms, well-to-do plant fanciers, botanic gardens, experiment stations, but particularly by the United States Department of Agriculture, which has or- _s * HEREDITY IN AMARANTUS. 251 Fic. B.— Seedlings from the small pigweed at the left, and from the big one at the right. Fic. C.— The pigweeds at blooming time. The parental character- istics apparently the work of a single generation—are shown to be hereditable. 238 CURRENT PLANT—BREEDING PRACTICE. ganized for this purpose the ‘ Office of Seed and Plant Introduction and Distribution,” in charge of David Fairchild. This office introduces prom- ising plants from all parts of the world, and subjects them to test on the grounds of the De- partment of the various experiment stations, and on the premises of private persons. Over fourteen ‘thousand selected entries appear on the inventory of the office. Some of these entries are species new to the country ; but most of them are new or untried forms of species already growing in North America. In many ways our domestic flora is being enriched from outside sources, and these additions in time will give rise to a variable progeny, or will furnish strong stock for hybridi- zation, and will affect the course of plant-breeding. I. LutTHER BURBANK. An editor of one of the great magazines asked me recently whether Luther Burbank were the only plant-breeder in the country. One who has read the current Burbankiana can well under- stand why the question was asked. If any reader has followed me this far, he will not need to ask a similar question. Yet if there are other plant-breeders, Luther Burbank stands alone. He is a private person, pursuing his work in his own way, and _ be- cause he loves it so well that he cannot forego LUTHER BURBANK. 239 it. He is a gardener of a new kind. Every plant appeals to him. This appeal is quite unlike the appeal that is made to the botanist or even to the horticulturist ; Burbank likes it because it is, a plant and because he would like to try to modify it. Therefore he grows everything he can, no matter where it comes from or of what kind. He cultivates with personal care, multiplies the stock to the limit of his capacities, scrutinizes every variation, hybridizes indiscriminatingly, saves the seeds of the forms that most appeal to him, sows again, hybridizes and selects again, uproots by the hundreds and thousands, extracts the delights from every new experience, and now and then saves out a form that he thinks to be worth introducing to the public. Every part of the work is. worth the while of itself; at every stage the satisfaction of it is reason enough for making and continuing the effort. Every form is interesting, whether it is new or the reproduction of an old form. He shows you the odd and inter- mediate and reversionary forms as well as those _ that promise to be of use to other persons. In all this there is neither magic nor conjura- tion. The methods are the common practices of all good plant-breeders, made unusually efficient, perhaps, by the geniality of the climate, the great scale on which some of the work is conducted, the wide variety of plants under experiment, and the — 7 ‘91 ‘spoq Uepivs pure sourviy Ss, yUeqIng Jo sul0g — ‘qf ‘DIA Pek Hl TOTTI ‘s yuRqing I9qINT 1v sueprey — “qT “DTT 242 CURRENT PLANT—BREEDING PRACTICE patient skill and good judgment of the man. He cares little for the scientific method, so long as the plants produce new forms. He will try to cross anything, no matter whether it has ever been crossed before or whether the crossing is in utter disregard of all acknowledged botanical relationships. Once when I asked him the botani- cal name of a plant, he replied that he did not know and did not care to know; for if he knew he would likely be bound by the book statements and he might be handicapped in his work. He is a bold worker, and this accounts for some of the odd results. Mr. Burbank is a plain, modest, sympathetic, single-minded man. He is not a wizard. The reporters have got hold of him and have abused their privileges because they have not known how to measure him and have not understood him. Perhaps he has not understood himself. He is kind-hearted and obliging; he has been drawn into discussions of all kinds of subjects, some of which nobody knows anything about; and persons have been led to think that he has occult knowl- edge. So far as these write-ups have tended to draw attention to the kind of work that he is doing, they undoubtedly have served a useful pur- pose; but many of them have really misrepre- sented the genius of the man. Luther Burbank stands for a great new idea in American horti- LUTHER BURBANK 243 culture, and it is time that we begin to recognize what this is. The practical results that Mr. Burbank has se- cured have been praised beyond all reason. His place abounds in interesting and surprising things, just as would be expected of any other man’s place if conducted under similar conditions. His work has been so much written about that it is not nec- essary to try to make any catalogue of the things that are under his hand. The number of really useful things that have been introduced by Bur- bank is proportionally small; although it is not too much to hope that some of his productions, as the plumcots, may be the starting points of strong and novel lines of evolution. Some of those that have been most heralded are of doubtful economic value. This is true, I think, of the much-vaunted spineless cactus. Several species of opuntia (to which genus Mr. Burbank’s spineless cactus be- longs) are spineless. Spineless cacti have long been known in Mexican and other gardens. By con- tinued selection the more or less spineless forms can be singled out and the smooth character per- haps intensified. Mr. Burbank may be able to eliminate the small spicules and to improve the plant in the edible qualities of its fruit and stems. There is no doubt that he has the spineless cactus in quantity (Fig. F). It is a pleasure to see him rub his face against the pads to deter- ‘'s, yuRqing 3v 1j0vo Sutrvoeq-oulds pur ssojouidg — "yy “OI LUTHER BURBANK 245 mine whether the spines are really there. But what use shall we make of it? It is said that we shall plant the deserts, for the cattle can eat this spineless cactus, and thus will the food supply of mankind be immensely multiplied and the welfare of the race enhanced. The cattlemen now singe the spines from the wild cacti by means of gaso- line torches, and this is much cheaper than to plant the desert; and experiments show that if the desert were planted with spineless cacti, the young plants would be destroyed if the cattle and jack-rabbits were allowed on the ranges: this would mean fencing the deserts. If the spineless cacti are grown from seeds, some of the progeny will probably be spiny; these and the native ‘seedlings will have to be uprooted and this will probably entail more expense than the en- terprise will be worth. If, in addition to this weeding, the plants are set out from cuttings, the desert becomes practically a cultivated ground. Moreover, it is undetermined whether Mr. Bur- bank’s cactus is really a desert form. Some of the deserts will be irrigated and then cacti will not be wanted ; and if the deserts are to be planted at all, it is a question whether cacti are the best plants with which to stock them. All this leads me to say that the value of Mr. Bur- bank’s work lies above all merely economic consid- erations. Heis a master worker in making plants | 246 CURRENT PLANT—BREEDING PRACTICE to vary. Plants are plastic material in his hands. He is demonstrating what can be done. He is setting new ideals and novel problems. Hereto- fore, gardeners and other horticulturists have grown plants because they are useful or beautiful : Mr. Burbank grows them because he can make them take on new forms. This is a new kind of pleas- ure to be got from gardening, a new and captivat- ing purpose in plant growing. It is a new reason for associating with plants. Usually I think of him as a plant-lover rather than plant-breeder. It is little consequence to me whether he produces good commercial varieties or not. He has a sphere of his own, and one that should appeal to a univer- sal constituency. In this way, Luther Burbank’s work is a contribution to the satisfaction of living, and is beyond all price. II. A PRAcTICAL PLANT-BREEDER. There are many wise and humble folk in many parts of the country who are making efficient his- tory in plant-breeding. I often feel that I should like to hunt them out and make them known to the world. They are mostly plant-lovers, whose chief reward is the joy that they derive from the work. I was struck with this many years ago when making a study of the evolution of the native plums, for patient souls had been at work on these fruits for years almost unknown of the world at A PRACTICAL PLANT—BREEDER. Q47 large, and had produced numbers of useful varie- ties ; and I have been similarly impressed in other excursions into plant evolution fields. There is another class of practical men who do ~ their work on a larger scale as a part of a thorough- going and well-known business enterprise. Such a business I am now to portray. I choose this particular instance only because I am some- what familiar with it and because it is near home. I had this man in mind when I wrote the lines on beans on pages 135 and 136 of this book. N. B. Keeney, Leroy, New York, was first a farmer. In war time he engaged in the produce business in Leroy, in a farming community. There was good trade in beans. The son Calvin N. Keeney became interested in the varieties of beans. He was attracted by their behavior in the field, and he began experiments to improve them by means of selection. From this it was but a step to the originating of new varieties. The son was taken into the business, the firm becoming N. B. Keeney and Son. The father is now dead, but the son continues the business. The business is primarily the growing of seed for seedsmen. It is devoted entirely to beans and peas. About two thousand acres in New York are devoted to beans, . and four thousand acres in Michigan to peas. In connection with the seed business is a can- ning factory, putting up beans, peas, and sweet corn. 248 CURRENT PLANT—BREEDING PRACTICE. The straw, husks, and other refuse could not be sold to advantage. It required an expenditure of five hundred dollars a year to dispose of the waste. In order to utilize this waste of the seed and canning businesses, a stock-feeding enterprise was estab- lished. The green pea vines, and corn refuse are ensilaged. The bean straw is fed tosheep. At pres- ent, the stock feeding comprises about one hundred and fifty hogs, three hundred steers, fifteen hun- dred sheep. These statements are made in order that the reader may see how far a bean-breeding and pea-breeding enterprise may lead. The main effort of the Keeney seed business is given to growing the leading varieties in quantity ; for in order to hold the best trade, it is necessary to keep every variety up to standard or even to im- prove it: therefore the entire enterprise becomes a practical plant-breeding business. Now and then new varieties are bred up and introduced ; and improved strains of old varieties are offered, often replacing entirely the old strains. In 1905 the following varieties of beans were grown in quantity; those marked with one star (*) are improved or selected strains, and those with a double star (**) are varieties of the Keeneys’ originating : — Best of All. *Black Wax, Cylinder Pod. Bismarck, Buist’s. **Black Wax, Fuller’s. Black Wax, Challenge. *Black Wax, Imp’d Prolific. A PRACTICAL PLANT—BREEDER. **Black Wax, Pencil-pod. Bountiful. **Brittle Wax. Brown Bunch. **Butter Wax, Maule’s. Champion Bush, Low’s. China Red Eye. Crystal Wax. Davis Wax. Emperor of Russia. Flageolet Wax, Crimson. Flageolet Wax, Purple. Golden Crown Wax. Golden Eyed Wax. Golden Wax, Grenell’s Imp. Golden Wax, Orig. Strain. **Golden Wax, Keeney’s Rustless. Goddard or Imp. Hort.Dwf. Hodson Wax. Horticultural Dwarf. Hort. Dwarf, Carmine Pod. Hort. Pole, Worcester Imp. Hort. Pole, Gold. Carmine. Hort. Wax, Rawson’s. Imperial Wax, Allen’s. Imperial Wax, Jones’s. Kidney, White. Kidney Wax, Wardwell’s. ** Kidney Wax, Round Pod. Longfellow. Marrowfat, White. *Medium, Burlingame’s. Mohawk, Early. 249 **Mohawk Wax. **Pea Beans, Boston Small. Pea Beans, Snowflake. Perfection Wax. Prolific, Powell’s. Prolific, Southern. Refugee, Extra Early. Refugee, Golden. Refugee, McKinley. Refugee, Round Pod or 1000 to 1. Refugee, Silver. *Refugee Wax, Stringless. Rust Proof Wax, Currie’s. **Saddle Back W ax, Burpee’s. Scotia. Six Weeks, Long Yellow. Six Weeks, Round Yellow. **Stringless Green Pod, Burpee’s. **Stringless Green Pod, Giant. Valentine Black. Valentine Ex. Ey. Red. *Valentine, Ex. Ey. Ex., Round Podded Red. Valentine, Hopkins’s Red. Valentine, White. Warren Bush. White Wax. **White Wax, Burpee’s New Stringless. White Seed Wax, Jones’s. **Yosemite Mammoth Wax. Keeney 250 CURRENT PLANT—BREEDING PRACTICE. This lst is interesting as showing the propor- tion of new or original to old or other varieties in a practical seed-breeding establishment. This list does not represent the whole number of varie- ties that Mr. Keeney grows, for the seed-breeder must test every new thing in his line and always be on the lookout for the chance to better the kinds that are in existence. Every year Mr. Keeney grows about two hundred kinds of beans in the test garden; and sometimes as many as six hundred different lots — some of them represent- ing different stocks or strains of the same variety —are grown and studied. To make any intelligent headway in breeding beans, the breeder must first know beans. He must know what the people want, what it is pos- sible to get, and all the good points and bad points of beans as to root and top, and bloom and_ pod and seed. This will prevent laborious mis- takes and economize much enthusiasm to be put into progressive work. Then he will look for natural sports that have some or all of the desired qualities ; thereafter the process is one of most rigorous selection until the stock breeds true. If the desired form or start does not appear, it may be necessary to set it off by crossing plants that have some of the desired characteristics; thereafter the process is one of selection, as before. Mr. Keeney says that he can increase A PRACTICAL PLANT-BREEDER. 951 or intensify a characteristic by means of selection, as well as eliminate the undesirable features. This is the whole plan of Mr. Keeney’s work. There is no mystery about it; but there is judg- ment of a kind that few men possess and a per- sistent process of selection such as few men have the heroism to maintain. If the breeder burns with a desire to have forms so distinct that he can attach a new name to them, he must caution himself at every point, else he will be introducing things before they are ready or which are of no gain to the world. New varieties of seed vegetables come slowly; and if they are not well bred (that is, not well selected), they will very soon break up into other forms or “run out.” Mr. Keeney puts his main effort in keeping the old varieties up to grade, and it is on these varieties that he makes the business pay. The making of new kinds of beans pays only in the intellectual satisfaction of it, and in the general standing that it gives the business. Mr. Keeney tells me that if he had never accomplished anything else in the breeding of plants, he would be content with having produced the Burpee Stringless Green Pod. To keep the stock up to grade, it is necessary to begin with seed that is not only “true to name,” so far as general varietal characteristics are concerned, but that is vigorous and with 252 CURRENT PLANT—BREEDING PRACTICE. strong hereditary or carrying-over power. ‘This seed is planted on well-prepared land that is adapted to beans. The tillage and general care must be of the best. The plantation is gone over with great care for “rogues” or untrue plants; these are pulled out. The thoroughness and con- sistency with which the “roguing” is done, will determine the result. This process is continued every year; and if one field or one man’s growing gives a better stock than any other, this product is used as stock-seed for all fields next year: thus the stock is always being renewed and rebred. Sometimes a single plant will be unusually good, and from this the whole stock may be renewed. For example, all the Mammoth-podded Sugar peas grown in America to-day came from a teaspoon- ful of seed that Mr. Keeney planted some ten or twelve years ago. Some fifteen or twenty years ago, Mr. Keeney found in a field of White Wax beans one plant that bore black seeds in stringless white pods. In three or four years he had saved a quart of promising seed. He planted this seed in an iso- lated rich farm garden. All came true but one plant: this plant was very tall and rank, and was green-podded. From this plant twenty-two varieties were produced, some of which were good enough to save and introduce. From the bulk of the original quart that came true, Mr. Keeney ceE"e A PRACTICAL PLANT—BREEDER. B53 produced the Yosemite Mammoth Wax, which is now a standard variety. The introducing of the “stringless” character into his beans has come about very largely by crossing with the Yosemite. In peas, Mr. Keeney grows the following list in quantity (he has specially selected strains of those marked with a star *) : — Abundance. Admiral. Admiral Dewey. Advancer. Alaska. Ameer. American Champion. *A merican Wonder. British Wonder. Champion of England. Claudit. Daisy, Carter’s. Duke of Albany. Duke of York. Dwarf Champion. Dwarf Telephone. Empire State. English Wonder. Everbearing. Excelsior, Gregory’s. Forty Fold. Glory. *Gradus or Prosperity. Green Gem, Sutton’s. Heroine. Hurst, William. Ideal, Sutton’s. Juno. King of the Dwarfs. *Laxton, Thomas. Long Island Mammoth. Market Garden, Horsford’s. Marrowfat, Black-eyed. Marrowfat, Early Marble- head. Marrowfat, Improved Sugar. Marrowfat, White. May Queen. Perpetual. Premium Gem. *Pride of the Market. ‘Prince of Wales. Profusion. *Prolific Early. *Prolific Early Market. Excelsior, Nott’s. *Extra Early, Pedigree. Extra Early, Trial Ground. First and Best. Forcing, Sutton’s. 954 CURRENT PLANT—BREEDING PRACTICE. Prolific, Laxton’s. Sugar, Very Dwarf. Prosperity or Gradus. *Sugar, Mammoth Podded. Reliance, Hurst’s. Sugar, Tall Gray. Seedling, Sutton’s. Surprise, Gregory’s. Senator, Improved. Telegraph (L. I. Mam). Shropshire Hero. *Telephone. *Stratagem. *Tom Thumb. Sugar, Dwarf Gray. Yorkshire Hero. The familiar Extra Early garden pea has been a subject of very careful breeding. The “Pedigree” strain has a continuous genealogy running back to 1890. In that year, it became apparent to Mr. Keeney that the general stock of this well-known ° variety was much mixed and run down. He therefore selected out a good stock, and soon de- veloped some twenty-four “ families” or lines of this variety; from these he later selected three lines, which were equally desirable, and repre- sented very closely his ideal of what the Extra Early should be. He still keeps up the selection ; and two or three times has discarded all his gen- eral seed-stock which he had himself produced, and has renewed the stock with a strain that he had been breeding up in the meantime. The work of choosing the initial departures and of making the primary seed-stock selections cannot be left to hired men; in fact, there are very few foremen or assistants who have the judgment and patience for the work: it must be a labor of love. Most persons do not have the courage to discard so PLANT—BREEDING IN EXPERIMENT STATIONS. 255 many plants. Mr. Keeney says that the success in seed-breeding lies in what you throw away. The satisfactory prosecution of all this work requires careful note-taking. Mr. Keeney fur- nishes, for example, such information as that given on page 256 for his customers, all taken directly from field notes. There. must also be personal records of the strains and stocks that are under manipulation. Mr. Keeney has kept the notes of his bean breed- ing in a specially prepared record book, with the entries running across two facing pages. ‘The headings of the various columns on these two pages suggest the kind of information that the breeder desires to have. (See page 257.) III. THe EXPERIMENT STATION WORK. Most of the agricultural experiment stations — and there is one to every state, territory, and _ nearly every Canadian province — are interested in concrete pieces of plant-breeding work. Through the extension work of these stations and of the agricultural colleges, the plant-breeding concep- tion is being carried to the people. These insti- - tutions are distributing selected and _ highly bred seeds, and are instructing their corre- spondents in the importance of quality in seed stock and the conditions that modify that quality. Perhaps the most fruitful extension work of this CURRENT PLANT—BREEDING PRACTICE. DNINYAONOD OT-ZI | QI- Po | oA & Be | Foe Fe | Be Os 3 do 5p ‘SUNITA §-* €-#Z | 62 $-F} ge-¥s | 18 ti-1 ¥P-F | 08 ' sme $o-4Z | TL nt te | eC t #e-%6 | 19 2-8 P-#S | OL gt-§ t-¥¢ | $8 ?}-8 #e-'¢ } %¢- € | O8 § tote | 6L oF-& at Co" ot v Og i ¥c-82 | 6P a 57-26 | 6P 23-8 | t7-%Z | $9 _ = S$ = 9 i=} a | “4 5 > B Bs e, Sa pate ler) Ses) See le Oct nymbp n Pee) ee hee Be BE | Beg Do QO — om om Sg "OR ‘Ssa0d ONINNAONOD SU.LON Ayyenb poor pod o[qIpy SH.LON SATIONPOIG *pooxy, powru AloyeanoYy "1OMOIS BUOYS pod o[qrpo osaery MOI ALVA SoLloyH eALONpPOIg ‘pooxy ‘OATIONPOIgG ‘ouly aAtponpoad A190 A ydvasoloy, poor, “YYMOLY WAT pod owospuvyyT ‘oAtonporg our ‘Ape Ayrpenb aegq ‘earyonporg uordueyg poaorduy Ajaeg VaAyXy ‘opvad ALB YJMOLS OAT “OUTST pooy) YJMOAS WA ‘OUT “SHUVNAY wos) WUNTUOT [enjodi9g B13) SNId ON ivsng Ssuypey proyorqrey Apregg qVIMOIAVI §,plojsiop] ‘Usprlvey JoyIVT IVSNG YOUTULI, Ajaeny puoosg ‘pog suo'y qIOUULV_, PUBS], SUO'T oun OULOLO PL Ayraedsorg 10 snpery IOUURD YoudAT PLO AVOT qsoq pue 4saly UIvIZG puNOAY) [VILY, Ajareny VAX Ajlvy BAYX SJJON ‘LOLS[OOXGT “‘SOILLOTUVA 257 PLANT—BREEDING IN EXPERIMENT STATIONS. “au “UHANWOAN ‘UAL "ON ‘d0d dO | *d0d AO IVIUL i *UVaAA NI *SHUVNAU om) Kaye yo 1 “an “LNV1Id aNoouy | ‘GALNVId WOHM Ad Ad VuS | WOTOO NI daLNVv1d LNGANOASAAS | LSAL TVIUL UVaAA ONIALS ‘dOUO LO NOLL TYOSad ‘CULN V'Id AU CH9Vd GNVH-LHDVIW) ‘CANNILNOO ‘SALON DNIGAANE *"§ Bu0IIg — "S'S SUMS — *§ F : ; “Ma AWN : ; ‘dod “a0d ONIMUVN |'HHOM ANNOUD | Ht,049 | *aaxas Fo aytyT — "1 “LNV'ld ‘AA VHS | “AZIS auooau | ON = .. | 10 TAVIS | 10 YOTOD AO XO100 410 WOTOO 10 UVHA) WAMOWD suoON —'O SNOIAGUd SNIALS ‘daaS SIHL GHONdGOUd HOIHM SLNVId dO NOILaINOSaa ‘daas FO NOL THOS ‘daas fo TouNnos Ca9Vd GNVH-LAVD ‘SALON DNIGAAUT . 258 CURRENT PLANT—BREEDING PRACTICE. kind is that conducted by the Ontario Agricultural College through the Ontario Agricultural and Ex- perimental Union. This is an organization of offi- cers, students and ex-students of the college. It has been in existence something more than twenty-five years. Through this union, since its organization, 37,416 experiments or tests on agriculture alone have been conducted on the farms. ‘The college has given much attention to the testing of the varieties of farm crops. Importation of the vari- ous cereals was begun twenty-five or thirty years ago. The institution has tested more than two thousand varieties of farm crops for a term of five years or more, some of them having been followed more than ten years. The college thus has on hand a vast amount of carefully tested and selected material with which to prosecute the codperative work. The plan has been to choose from two to four of the most successful varieties of the various farm crops and put them out among the codperators throughout the province. ‘The college has under test at the present time two hundred varieties of potatoes from which selections are made for the cooperative tests. It has fifty varieties of sweet corn under study, and in nearly all of the farm and horticultural crops it is in a similar situation as regards material for the codperative work. So far as the mere testing of varieties of ordinary farm crops is concerned, relatively little will be WORK IN ONTARIO. 259 done in the future ; but the purpose is to continue the work with strains of those varieties that are the result of careful selection at the college. Several years ago work was begun in selecting wheat, barley, oats, and other grains by individual plants and in propagating these plants until a sup- ply was secured for the farmer. This year there were harvested two acres of oats that came from a single seed three years ago. It is remarkable that such a supply can be secured in so short a time. In 1905 there was secured a yield of 1929 pounds of barley and of 3439 pounds of oats that were the progeny of a single seed sown in 1903. It is also stated that for the more remote future the work will be with hybrids which they are now breed- ing with apparent success to produce more desir- able types with larger yielding qualities. All tests made by the farmers are duplicated on the college grounds. It is now proposed to establish a complete set of such experiments in each county in the province, the party conducting the work to be remunerated for the actual labor involved. These statements show how extended and effec- tive certain kinds of practical plant-breeding work have come to be. An examination of the recent annual reports of the experiment stations in the United States show that at least twenty-eight of them report specific plant-breeding work as in progress. The plants 260 CURRENT PLANT—BREEDING PRACTICE. that are mentioned comprise the following: cot- ton, sorghum, corn, grasses, buckwheat, millet, wheat, rye, oats, barley, eggplant, tomato, red clover, tobacco, sweet corn, sugar beet, timothy, alfalfa, potato, pea, bean, apple, peach, cherry, plum, strawberry, blueberry, grape, date, buffalo- berry, currant, gooseberry, raspberry, ornamental shrubs, flowers, forest trees. It would manifestly be impossible to give even arunning sketch of all this interesting plant-breed- ing work. Results may not be forthcoming as rapidly as we would like, but it is apparent that such an amount of effort concentrated on one gen- eral line of effort is bound to accumulate surprising results in the years to come. Merely as examples of the nature of the problems lying in this unex- plored field, I insert a brief description of two pieces of breeding work now in progress and very - different in kind. Breeding Hardy Fruits for the Prairie Northwest. By N. E. Hansen. There are three headings under which this subject may be considered : (1) importation; (2) exploration ; (5) amelioration. By importation we secure the best plants from other countries. In pursuance of this policy I import plants every year from various countries of the Old World. FRUITS FOR DAKOTA. 261 By exploration is meant searching for desirable variations from the normal type of fruits in our native woods and prairies. I have done much of this kind of work, especially in the range country from the Missouri River west to the Black Hills. By amelioration is meant the improving of this mate- rial gathered from various parts of the world. We should take all native plants of any value and try by crossing them with desirable imported plants to secure new plants combining the desir- able characteristics of both races. Over a large area of the prairie Northwest, many of the fruits grown in the eastern and southern states are deficient in hardiness. This has been demonstrated by thousands of planters. It has been estimated that it cost over one hun- dred million dollars to learn that the varieties of apples from the milder climate of western and southern Europe are not adapted to this new prairie region. It begins to be evident that all this ex- perience is another proof of De Candolle’s law, that several thousand years are needed to produce a modification in a woody plant which will enable it to support a greater degree of cold. But that nature is equal to such a task is shown by the fact that woody plants, such as box elder and the red cedar, extending over a wide area, differ greatly in hardiness. ‘The red cedar and box elder from the - southern and eastern range of their limits winter- 962 CURRENT PLANT—BREEDING PRACTICE. kill at the northern limits, while the local form of the species is hardy. In other words, it is possible for nature through thousands of years to change the constitution of a plant as to its ability to endure greater cold, but it is not an experiment for man to undertake. Inherent hardiness must be present in at least one of the parents of the seedling ; that is, hardiness cannot be secured from tender varieties by selection. It must either be present in both parents or transmitted from one parent, the same as any other characteristic. Plants can be bred more resistant to cold by cross- ing with some hardy species. Methods of Work. — In general, where no cross- ing is done, the principle followed is that laid down by Darwin and others: ‘“ Excess of food causes variation.” Choice seedlings are started in flats and transplanted to the field when large enough, in highly manured soil. In some cases it is best to sow seed thinly in nursery rows and transplant when one year old. At fruiting time the best few are selected, the remainder dug with a tree-digger and destroyed by fire. After endeavoring in vain for several years to cross fruit blossoms in the breezy climate of South Dakota, where spring is sometimes back- ward and then the blossoms come on with a rush, I decided to do the work under glass. While visiting orchard houses in Europe in 1894 and FRUITS FOR THE COLD PRAIRIES. 263 again in 1897 the thought came to me that this method of raising fancy fruit could be utilized in experiments in the prairie Northwest. The appli- cability of this method elsewhere remains to be determined. The use of dwarf stocks is necessary as the paradise for the apple, quince for the pear, and the western sand cherry for the stone fruits. The South Dakota legislature of 1901 granted means for erecting the first fruit-breeding green- house ever constructed. Since then experiments have been limited only by the space available. Much more could have been done with a larger greenhouse. I trust that future legislatures will provide additional facilities. Illustrations and de- scriptions of these breeding houses may be found in Bulletin 88 of the South Dakota Experiment Station. As a result of this appropriation, and the lib- erality of the regents of education in affording needed storage cellars and other facilities, we are able to announce the production of many inter- esting hybrid fruits, many of them combinations made for the first time. Some of them are hybrids of the South Dakota sand cherry with the peach, nectarine, Japanese plums, a Chinese apricot, and a purple-leaved plum from Persia. The work with the western Sand Cherry (Prunus Bessey?) is reported in Bulletin 87. Progress is also being made in originating hardy cherries, strawberries, 264 CURRENT PLANT—BREEDING PRACTICE. and raspberries. By far the most extended ex- periment on record in the making of graft-hybrids of the apple has been undertaken, and we await the fruiting of the resulting plants with interest. In ornamentals the main work done has been cross- ing the wild Dakota and Siberian roses with choice double roses. If sufficient greenhouse facilities are afforded, the propagation of such new seed- lings as give promise of permanent value will be pushed, so that they may be distributed for trial elsewhere as rapidly as possible. The advancing northward at least five hundred miles of the suc- cessful cultivation of the cherry, peach, and apri- cot, and that of winter apples, we trust will be some of the results of erecting this novel work- shop for the invention of new hardy fruits. Considerable success has been secured in has- tening the fruiting of cross-bred seedlings. For instance, strawberries originated one winter by crossing the wild with the tame have been raised up to fruiting size the same year outdoors and fruited in pots under glass the following winter. This saves much time in selecting varieties for propagation, and also hastens the work of propa- gation by our being able to pot many layers before transplanting to the field. In handling a quarter of a million fruit seed- lings, I find many interesting side lines of investi- gation presenting themselves, but just now the FRUIT—BREEDING IN DAKOTA. 265 main effort must be to originate a few varieties of the various orchard and small fruits worthy of a permanent place on the present limited fruit list of the prairie Northwest. In handling so many thousands of seedlings, my endeavor in recent years has been to get some clew to the quality of the fruit while the plants are yet small. It would greatly lessen the labor involved. No positive correlations of this kind have as yet appeared. However, the two essen- tials of vigor and perfect hardiness are insisted upon from the beginning. With the sand cherry, of which I have a patch of over twenty-five thou- sand plants of the third generation under cultiva- tion coming into bearing in the year 1905, I have found some seedlings that are quite free from mildew which so commonly affects the plant, es- pecially in moist seasons. It is my belief that we can breed a mildew-resistant race of this prom- ising prairie fruit. In a patch of over six thou- sand native plum seedlings I insisted on, as far as possible, perfect foliage as well as fruit of large size and good quality. In a patch of over three acres of strawberries of half-wild, half-tame ances- try, I insist on the leaves being free from rust (Ramularia), but it may be impracticable to do this wholly as. our wild strawberries have the foliage affected in this manner. Whether we get our blight-proof apple remains to be seen. Any 266 CURRENT PLANT—BREEDING PRACTICE. plant that will not endure forty degrees below zero with the ground bare of snow and come out unharmed the next spring is rejected. In disease resistance some peculiar facts crop out. For ex- ample, some pure wild roses mildew, while their hybrids with cultivated roses are free. | I have learned to look upon a species of plants — only as a bundle of characteristics, more or less © definite in its make-up, to be modified to suit our © needs. A new seedling is really a new invention. Although legally “a gift of God,” it is the result of the creative forces of nature under the guiding hand of man. Part of our labor is to improve nature’s handiwork the better to adapt them to the needs of a civilization ever growing more. complex. Cornell Timothy-breeding. By SAMUEL FRASER. The prosperity of a good part of the country _ rests directly on grass. Timothy grass is the most important single crop in New York State. Yet we have no varieties of timothy, as there are of wheat and corn and beans. No good farmer would sow wheat without knowing the variety, for varieties differ in yield, hardiness, quality of grain, or other excellences. The experiment sta- tion of Svalof, Norway, has shown that the yield of timothy, for hay, may be considerably increased ‘yueld opsurs @ st dumyo yoeq = ‘uOTyesyseAut ATJOUIT, [[IUIOD —“yH ‘DIT ‘Q0UdIOTJIP JO 9o1Zop pus pury UoUTUIOD B SuLMoOYsS ‘opis Aq Opts Surmois ‘syuvpd Aqjouly Sull[pses OMT, — "fH ‘YI TIMOTHY—BREEDING. 269 by the selection of varieties. It is to be expected that plants possessing other permanent characters SPE NS ne AL ES a5 eS rs eee i Baa aE Sar: ‘ of economic value may be found, and that we may secure some varieties which will be early in bloom Fia. I. — Variation in heads of timothy. 270 CURRENT PLANT—BREEDING PRACTICE. and others which will mature later ; some possess- ing strong and long stolons and practically no corm, and therefore adapted to withstand grazing; and still others which produce abundance of fall feed. A careful study of timothy will show that it is not all alike. It varies greatly; it is reasonable to expect that some of these variations are heredi- table, and that this hereditability can be inten- sified or “fixed.” In order to test these points, an experiment was begun in 1903. Timothy seed was secured from 280 sources in this country and ~ abroad. With some selections made from indi- vidual plants on the University farm, 12,600 plants were set in the fall of 1903 in 300 plats. During 1904 and 1905 the planting of progeny, selected for various characteristics, has increased the number of plats to about 450, with 20,000 individuals. These, with a grass garden in which there are 6000 individual plants of about 50 species, many being the progeny of selected plants, cover about 10 acres of ground. There are 20 miles of rows of timothy plants. More than 100,000 distinct records have been recorded in a single year on 9000 of these plants. All plats contain 42 plants, 30 inches asunder in rows 30 inches wide and in 2 rows of 21 each. Every third plat is sown with a standard and uniform lot of seed grown on the University TIMOTHY—BREEDING AT CORNELL. 271 farm, and in 1905 all new check plats were sown with seed from one plant. The check plats meas- ure any variation in soil conditions, and each ic wake en NAYES Fic, J.— A timothy plant that runs almost wholly to leaf. variety or sample is measured by the yield or stand of the check plat alongside. Example : — Pee 2 BAe Gk. 8. 9 10 Cc c Cc c It was soon apparent that the widest variations 272 CURRENT PLANT—-BREEDING PRACTICE. would be developed in the plants. These varia- tions are of the following kinds : — (a) In duration: some annual, others perennial ; (6) In stooling power: some ten heads, others two hundred and fifty; some have longer stolons than others ; (c) In time and manner of bloom: some a week or ten days earlier than others; (d) In character of leaf: some are long, others short; broad, narrow; smooth, rough; erect, spreading ; (e) In shape and size of head and seed-produc- — tion: large, thick heads can carry plenty of seed ; some plants that promised well for pasture had very poor heads and little seed; (f) In character of culm: some erect, others spreading ; (g) In general time of maturity: some develop early and by August will have a second lot of heads in bloom; others will not; (h) In character of inflorescence: panicled and not ; (2) In vigor: in 1904, out of 9114 plants set in ~ fall of 1903 from American-grown seed, 37 per cent were dead in 8 months, and 40.5 per cent in the first year. By 1905, or nearly 2 years after planting, 49.4 per cent had succumbed. (7) In yield: in 1904, of the 5619 survivors above-mentioned, 103 yielded between jfand 4 ae SS Nn ie ge a mee ey ~*~ Fic. K.— A timothy plant that runs much to seed. 2974 CURRENT PLANT-—BREEDING PRACTICE. pound hay and 3 yielded half a pound; 5500 yielded less than j pound. In 1905, of the 4612 survivors, 4 yielded over 1} pounds of hay and 48 over one pound. In Figs. H to L are shown some of the kinds of variation or differences in timothy plants. Of course, nearly all the plants turned out to have no superior merits. In 1905, plants had been grown from seeds of ninety-three selected plants and three varieties were secured — enough for ninety-six plats. The characters were such as: heavy yield, poor yield; coarse stem, fine stem ; early in bloom, late in bloom; thin heads, thick heads; broad leaves, narrow leaves; tall; leafy, not leafy; etc. All of these plats are checked by having a check plat beside them. All check plats are sown with seed from one plant, No. 9.08, the heaviest yielding plant having two years’ record. In addition, centgener plats (containing one hundred plants placed in ten rows of ten each, six inches apart) were set from the thirteen heaviest-yielding plants. These are checked with No. 9.03 plants and have five foot alleyways be- tween, to permit of covering the plat with canvas to prevent cross-pollination. Thus far the prog- eny from three heavy-yielding plants selected in 1904 have transmitted heavy-yielding charac- ters, and the progeny of weak plants are weak and small in size. Fic. L.— A productive timothy plant. 2°76 CURRENT PLANT—-BREEDING PRACTICE. IV. Unitep STATES DEPARTMENT OF AGRI- CULTURE. Probably the largest organized governmental plant-breeding enterprise in the world is in the United States Department of Agriculture. The “ Laboratory of Plant-Breeding” is in charge of Dr. H. J. Webber, himself an expert breeder. Aside from the cotton-breeding, citrus-breeding, and other investigations by Dr. Webber, the fol- lowing work was going forward in 1905 : — Alkali and Arid Plant-Breeding, Thos. H. Kearney and L. L. Harter. Tobacco-Breeding, A. D. Shamel, W. W. Cobey, and Dr. W. W. Garner. Corn-Breeding, C. P. Hartley and E. B. Brown. Cotton-Breeding, Dr. D. N. Shoemaker, Prof. D. A. Saunders, E. B. Boykin, Prof. A. W. Bennett, Prof. S. M. Bain, and H. A. Allard. Oat- and Potato-Breeding, J. B. Norton. Wheat-Breeding, M. A. Carleton. Breeding of Disease-resistant Cottons, Watermelons, Cow peas, etc., W. A. Orton. Sugar-Beet-Breeding, Dr. C. O. Townsend. Aside from the above principal lines of work, investiga- tions are being conducted by the Department in the breeding of carnations, roses, dahlias, lettuce, apples, pears, and other plants. In order to explain the point of view and to exhibit the methods of the work of this labo- ratory, I have secured from Dr. Webber and Mr. Carleton brief summaries of some of the pieces of work ; and these statements comprise the remain- der of this chapter, Fic. M. — Citranges (Hybrids of orange and Citrus trifoliata). ‘Top fruit Citrus trifoliata. Top pair, Rusk Citrange. Bottom pair, Willits Citrange. 3% nat. size. Reduced from colored figures in Yearbook of the Department of Agriculture. 278 CURRENT PLANT—BREEDING PRACTICE. Citrus-breeding. By Herpert J. WEBBER. Work on the production of frost-proof types was started first in 1893-1894, but the hybrids were lost by accident; other hybrids were made in 1896 and 1897. Sl a ee Medium - - - - -|- ---- er |. -points|Medtuin Weakl-----| >.) |>as> =A aanieiee Excellent.—--|----- Yield Gaol. oes |] eee Medium. -.--|----- ___points.|Light Medium (P. B, Form 15.) Sissies tbat Wo....dnKacnn eee. Wow boc ove cacce Sead eat - th beets wee SEE a at PO! Eo oh as ae ote Oat ete ~~ A ee am a LAINE. to Mile 4 edo . ro ys ee oaus — eae sees 7 = - see ee i i a oe hen eaten hel PCA a6 qutneso| phar Cb ouhihak wa" : eee ae ~yftesi| ie *) 8, af vis a LECTURE VI. POLLINATION ; OR HOW TO CROSS PLANTS. 1. THE STRUCTURE OF THE FLOWER. POLLINATION is the act of conveying pollen from the anther to the stigma. It is the manual part of the crossing of plants. The word fertilization is often used in a like sense, although erroneously; for it is the office of the pollen, not of the opera- tor, to fertilize or fecundate that part of the flower which is to develop into a seed. The chief requirement in pollinating flowers is to know the parts of the flower itself. The con- Fic. 1. — Bell-flower. spicuous vr showy part of the flower is the envelope, which is endlessly modified in size, form, and color. 331 oon POLLINATION, This envelope protects the inner or essential organs, and it also attracts insects, which often perform the labor of pollination. ‘This floral envelope is usu- ally of two series or parts,—an outer and commonly green series known as the calyx, and an inner and generally more showy series known as the corolla. ‘These two se- ries are well shown in the bell-flower, Fig. 1. The calyx, with its re- fae ce [) flexed lobes, is at C,& aoe and the large bell-form ca SH ae portion is the corolla. : yy a When the calyx is com- \{ l posed of separate parts or leaves, each part is — called a sepal; in like manner each separate part of the corolla is al a petal. In the lily, ae Fig. 2, there is no dis- tinction between caly z Fic. 2.— Flower of white lily. and corolla; or, it may be said, the calyx is wanting. These envelopes of the flower are often much disguised. This is particularly true in the orchids, one of which, a lady-slipper, is illustrated in Fig. 3. The sepals are seen at DD. They are apparently only two, but there is reason to believe that the lower sepal THE ESSENTIAL ORGANS. 3o3 is really made up of a union of two. The three inner leaves are the petals, the lower one, H, being enlarged into the sac or slipper. The most important organs of the flower, how- ever, to one who wishes to make crosses, are the so-called sexual organs, the stamens and pistils. They can be readily distinguished in the p lily, Fig. 2. The six bodies shown at S are the ends of the stamens, or so- called male organs. These stamens gen- erally have a stalk or stem, known as a filament, and the en- larged tip as the anther. It is in this anther that the pol- len is borne. The pollen is generally made up of very mi- Fic. 3.— Flower of greenhouse cypripedium. nute yellow or brown- ish grains, although it is sometimes in the form of a more or less glu- tinous or adhesive mass, as in the milk-weeds and orchids. ‘The irritating dust which falls from the corn tassels at the later cultivatings is the pollen. 334 POLLINATION. The pistil, or so-called female organ, is shown at OP, Fig. 2. The enlarged portion at O is the ovary, which will develop into the seed-pod. The stigma, or the enlarged and roughened part which receives the pollen, is at P. Between these two parts is the slender style, a portion which is absent in many flowers. | The stamens and pistils are known as the essen- tial organs of the flower, for, whilst the calyx and corolla may be entirely absent, either one or both of these organs is present; and these are the parts which are directly concerned in the reproduction of the species. Like the floral envelopes, these essential organs are often greatly modified, so much so that botanists are sometimes perplexed to distinguish them from each other or from mod- ified forms of the petals or sepals. The particu- lar features of these organs which the plant-breeder must be able to distinguish are the anther and the stigma; for the anther bears the pollen, and the stigma must receive it. In Fig. 1, the stamens are shown at E. In the flower A, which has just expanded, these stamens are rigid and in condition to shed the pollen, but in the flower B, they have shed the pollen and have collapsed. ‘The stigma in this case is divided into three parts, but when the flower first opens, these parts are. closed to- gether, H in flower A, so that it is impossible that they receive any pollen from the same flower; ‘ THE ESSENTIAL ORGANS. SoU when the stamens have withered, however, as in B, the stigma, H, spreads open and is ready to Fic. 4.— Flower of night-blooming cereus. receive any pollen which may be brought to it by insects or other agencies. In this case, the ovary 336 POLLINATION. or young seed-pod, which is in the bottom of the flower, is not shown in the engraving. Some of the particular forms of essential organs are well illustrated in the accompanying photo- graphs. In the night-blooming cereus, Fig. 4, the many-rayed stigma is shown just below the Fic. 5. — Flower of the shrubby hibiscus (Hibiscus Syriacus). centre of the mouth of the flower, and the nu- merous stamens are arranged in a circular manner outside of it. The many petals and numerous spreading sepals are also well shown. The hibis- cus, Fig. 5, has a central column with the anthers hanging upon it, and a large stigma raised beyond STAMINATE AND PISTILLATE FLOWERS. 337 Fic. 6.— Bugbane (Cimicifuga racemosa). them. The wild bugbane, or cimicifuga, is seen in Fig. 6, natural size. Here is a long spike or cluster of flowers. At the top are the unopened buds, in the centre the expanded flowers with the floral envelopes fallen away, the fringe-like stamens very prominent, — and below are seen the pis- tils, the stamens having fallen. These pistils will now ripen into pods, but the tip-like stigma may still be seen on them. The stamens and the long protruding style, tipped with its stigma, are also shown in the fuchsia, Fig. 15. The essential organs of orchids are cu- riously disguised. They are combined into a sin- gle body. In the lady- slipper, Fig. 3, the lip-like stigma is shown at P. Upon either side, at its 338 POLLINATION. base, is an anther S. Projecting over the stigma is a greenish ladle-like body, T, which is a trans- formed and sterile anther. In all lady-slippers, these organs are essentially the same as in the drawing, although they vary much in size and shape; but in most other orchids, the two side anthers, S, are wholly wanting, and the terminal organ, T, is a pollen-bearing anther. In numer- ous plants, there are many distinct pistils in each flower. Such is the case in the strawberry, where each little yellow ‘‘seed” on the ripened berry represents a pistil; and the blackberry and the raspberry, where each little grain or drupelet of the fruit stands for the same organ. A flowering raspberry is illustrated natural size in Fig. 7, for the purpose of showing the ring of many anthers near the centre of the flower, inside of which, in the very centre, is a little head of pistils. It frequently occurs that the stamens and pistils are borne in different flowers, rather than together in the same flower as they are in the examples which we have studied. In these cases the flower is said to be staminate, or male or sterile, in one case, and pistillate, female or fertile, in the other case. If these two kinds of flowers are borne together upon the same plant, as in pumpkins, melons, cucumbers, chestnuts, oaks, and begonias, the plant is said to be monecious ; but if the stami- nate and pistillate flowers are on entirely different STAMINATE AND PISTILLATE FLOWERS. 339 plants, as in willows and poplars, the plant is diw- cious. The two kinds of squash flowers are shown in Fig. 8. The pistillate flower is on the left, and it is at once distinguished by the ovary or little squash below the colored portion, Fic. 7.— Blossom of flowering raspberry (Rubus odoratus). or corolla of the flower. ‘The lobed stigma is seen in the centre. ‘The staminate flower is on the right. It has a longer stem, no ovary, and the anthers are united into a conspicuous cone in the centre. The flowers expand early in the morning. Insects carry pollen to the pistillate flower, which 340 POLLINATION. then begins to set its fruit, whilst the staminate flower dies. The flowers of the common wild clematis are shown in Fig. 9. Upon the right 0 ee et 4 Fic. 8.— Squash flowers of each sex. are the sterile flowers, which are wholly stami- nate. On the left, the flowers with larger sepals —the petals are absent — have a cone of pistils in - STAMINATE AND PISTILLATE FLOWERS. 341 the centre, and a few short and sterile stamens spreading from the base of the cone. These dif- ferent flowers are borne on different plants in this species of clematis, and the plants are therefore practically dicecious, because the stamens of the pistillate flowers generally bear no pollen. A sim- ilar mixed arrangement occurs in some strawber- Fic. 9.— Flowers of clematis (Clematis Virginiana). ries, except that there are no purely staminate flowers. There are purely pistillate varieties, others, like the Crescent, with a few nearly or quite abortive stamens at the base of the cone of pistils, and others in which the flowers are per- fect or hermaphrodite, that is, containing the two sexes. 342 POLLINATION. The compositous flowers — like the asters, daisies, ~ goldenrods, sunflowers, dahlias, zinnias, chrysan- themums, and their kin—need to be considered in still a different category. In these plants, the head, or so-called flower, is an aggregation of sev- eral or many small flowers or florets. Each seed in a sunflower head, for example, represents a dis- tinct flower. Sometimes all of these flowers are perfect, — contain the two sexes, — and sometimes they are pistillate or staminate in different parts of the head; and in some cases the plants are dicecious. In many plants of the composite fam- ily, the flowers near the border of the head are unlike those of the centre or disc, in having a long ray-like corolla; and these ray-flowers are frequently of different form from the others in the character of the essential organs. Very frequently the ray-flowers are pistillate, whilst the disc-flow- ers are generally hermaphrodite. ‘The anthers, in these plants, are united in a ring closely about the style and below the stigma. The ovary, as we have seen, ripens into the pod, berry, or other fruit; but it is not able to bear seeds until it is assisted by the pollen. The pollen falls upon the roughish or sticky surface of the stigma, and there germinates or sends a minute tube downwards through the style and finally reaches the ovule, which, when fertilized, rapidly ripens into the seed. The nature of this COMPOSITOUS FLOWERS. 343 fecundation is not germane to the present subject ; but it may be said that only one pollen grain is necessary to the fertilization of a single ovule, but the addition of a superabundance of pollen greatly stimulates the growth of the fleshy or enveloping parts of the fruit. It is important that the person who desires to cross plants should become familar with the stigma when it is “ripe,” receptive, or ready to receive the pollen. This condition is gen- | erally indicated by the glutinous or sticky or moist condition of the stigma, or in those stigmas which are not glutinous it is told by the appearing of a distinctly roughened or papillose condition. This receptive condition generally occurs about as soon as the flower opens. If pollen is withheld, the stigma will remain receptive much longer than when fertilization has taken place, —in some flow- ers for two or three days. The pollen is discharged from the anther in — various ways, but it most commonly escapes through a chink or crack in the side of the anther. Sometimes it escapes through pores at one end of the anther; and in other cases there are more elaborate mechanisms to admit of its dis- charge. In most plants, the anthers and stigma ~ y, in the same flower mature at different times, so that close-fertilization or in-breeding is avoided... This is well illustrated in the bell-flower, Fig. 1. Here the anthers wither and die before the stig- 344 POLLINATION. matic lobes open. In other cases, the stigma matures first, although this is not the usual con- dition. II. MANIPULATING THE FLOWERS. Weare now familiar with the essential principles in the pollination of flowers. Before a person pro- ceeds to operate upon a flower with which he is unfamiliar, he should carefully study its structure, so as to be able to locate the different organs, and to discover when the pollen and the stigma are ready for the work. The first and last rule in the pollinating of plants is this: Hyzercise every precaution to prevent any other pollination than that which you design to give. The anthers, therefore, must be removed from the flower before it opens. This removal of the anthers is known as emasculation. Just as soon as this is done, tie up the flower securely in a bag to protect it from foreign pollen which may be brought by wind or insects. As soon as the stigma is ripe, remove the bag and apply the de- sired pollen, placing the bag on the flower again, where it must remain until the seeds begin to form. The stigma may be receptive the day fol- lowing emasculation, or, perhaps, not until a week afterwards. Much depends upon the age of the bud when emasculation takes place. It is gener- EMASCULATING. B45 ally best to delay emasculation as long as possible and not have the flower open; but the operator must be sure that the anthers do not discharge or that insects do not get into the flower before he has emasculated it. The bud at B, in Fig. 3, is Fic. 10.— Tobacco flowers, showing the parts of the flower, a bud ready to be emasculated, and an emasculated subject. nearly ready to emasculate. The older buds on the top of the spike of bugbane, Fig. 6, are ready to operate upon; and so is the bud seen at the left in Fig. 7. The manner of emasculating the flower varies 346 POLLINATION. with the operator. It is a common practice to clip off the anthers with a pair of small scissors, or to hook them out with a bent pin or a crochet hook. Others use tweezers. For myself, how- ever, I do not like any of these methods, because the anthers are apt to drop into the bottom of the corolla, where it is sometimes difficult to rescue them; and if one uses tweezers, there is always danger that the anthers may be crushed and that some of the pollen may adhere to the instrument and contaminate future crosses. I therefore usu- ally cut the corolla completely off just above the ovary, with a pair of small, long-handled surgeon’s scissors (see Fig. 12), removing everything but the pistil. The operation is explained in Fig. 10, which shows the tobacco flower. The flower at the left shows the pin-head stigma in the centre of the throat, and the five anthers surrounding it. The second flower is spread open for the purpose of showing these organs. ‘The third figure is a bud in the right condition for operation. The right-hand figure shows this bud cut around with the points of the scissors, leaving only the pistil. The line at W, in Fig. 2, shows where the flower of the lily might be cut off. ‘The manner of oper- ating upon a compositous flower is shown in the picture of the zinnia, Fig. 11. In this plant the outer florets of the head are pistillate, whilst those of the disc are perfect. It is only necessary, EMASCULATING. 347 therefore, to remove the central stamen-bearing flowers before any of them open, and to cover the flower up before any of the pistils near the border rs . - nen CTR ESRI aS ECA sae) ese paeRe a AG a 5 bee i ea act RR A alia ance WO acaba Fig. 11. — Zinnia flowers; the upper head ready for emasculation, the lower one showing the operation performed. have protruded themselves. The upper head in Fig. 11 shows the untreated sample, whilst the lower one shows the same with the cone of central 348 POLLINATION. flowers pulled out. This treated head should now be covered, to await the maturing of the stigmas. In many compositous plants, however, the case is not so simple as this, because all the flowers are perfect. In such cases, nearly all the florets should be removed from the head, and a few remaining ones emasculated in essentially the same manner as described for the tobacco, Fig. 10. Whenever flowers are borne in clusters, nearly all of them should be removed and the attention confined to only two or three of them. One is then more cer- tain of getting seeds to set. In some cases, like the apple cluster, only one or two flowers of any cluster ever set fruit, and the operator should then choose the two or three strongest and most prom- ising buds, and cut all the. others off. Flowers which bear no stamens, as the pistillate flowers of squashes, strawberries, and many other plants, of course do not require emasculating. They should be tied up while in bud, however, to prevent the access of any foreign pollen. Indian corn is a case in point. ‘The pistillate flowers are on the ear, each kernel of corn representing a single flower. The silks are the stigmas. If it is desired — to cross corn, therefore, the ear should be covered before any silks are protruded, and the pollen should be applied some days later, when the silks are full grown. ‘The staminate or male flowers are in the tassel. : APPLYING THE POLLEN. 349 The pollen should be derived from a flower which has also been protected from wind and in- Fic. 12.— Instruments used in pollinating flowers, natural size. Pin scalpel, scissors, lens. 350 POLLINATION. sects, because foreign pollen may have been dropped upon an anther by an insect visitor and it may be unknowingly transferred by the operator. The pollen-bearing parent needs no operation, of course, but the flower should have been tied up in a bag when it was in bud. The pollen is best obtained by picking off a ripe anther and crush- ing it upon the thumb-nail. Then it is trans- ferred to the stigma by a tiny scalpel made by hammering out the small end of a pin, as shown, full size, at the left in Fig. 12. The stigma should be entirely covered with the pollen, if pos- sible. It is often advised to use a camel’s hair Fic. 13. — Ladle for pollinating house tomatoes. brush to transfer the pollen, but much of the pollen sticks amongst the hairs of the brush and is ready to contaminate a future cross; and where the pollen is scarce it cannot be conserved to advantage by a brush. In some cases the pollen is discharged so freely that the anther may be rubbed upon the stigma, or even shaken over it, but in most instances it will be necessary to actu- . ally place the pollen upon the stigma with some hard instrument. When pollinating house-grown melons and cucumbers, the staminate flower is broken off, the corolla stripped back, and the KEEPING THE POLLEN. | DDE anther-cone inserted into the pistillate flower, where it is allowed to remain until it dries and falls away. In pollinating house tomatoes, an implement shown in Fig. 13, one-third size, is used. This is simply a watch-glass, T, secured to a handle. When the house is dry, at midday, the watch- glass is held under the flowers, which are tapped, and the pol- len falls into the glass. The glass is then held up under another flower until the stigma rests in the pollen. It should be said, however, that this pol- lination of tomatoes is for the purpose of making the fruit set in the absence of insects, not to effect a cross. If the latter purpose were the object sought, the flowers which are to bear the seeds would need to be emasculated. Sometimes it is impossible to secure the pollen at the time the stigma is ready. In some cases of this kind, the intended parents can be grown under glass so as to bring them into bloom at the same time. In other cases, it is necessary to keep the pollen for some time. The length of time that pollen will keep varies with the species and Fic. 14. — Bag for coy- ering the flowers. 352 POLLINATION. al probably also with the strength and vigor of the plant which bears it. As a rule, it will not keep } more than a week or two, and, in general, it may | | Secs ee aay = Fic. 15.— Fuchsias, showing the stamens and pistils, and a bud ready to be emasculated. be said that the fresher it is the better it may be expected to act. || It is best kept in dry and tight BAGGING THE FLOWER. 353 paper bags, such as are used for covering the flowers. Something more should be said about the bags which are used for covering the flowers. After having tried every kind which is recommended, I find grocer’s manilla bags much the most satis- factory. For most flowers the four-ounce size is the handiest. When the bags are still flat, as Fig. 16.— Fuchsia flower emasculated. they come from the packages, a hole is made through the two overlapping folds near the open- ing, and a string is passed through it and then tied at one of the folds, as shown in Fig. 14. The bag is then ready for use. Before it is put on the flower, the lower end of it is dipped in water to soften it so that it can be puckered tightly about the stem and thereby prevent the 354 . POLLINATION. entrance of any in- * sect. A bag is put upon the seed-bear- ing flower when emasculation is per- formed, and upon the intended pol- len parent when the flower is still in bud. The bag may be removed fae —& = from the emascu- (| Sy : lated flower from time to time to ex- amine the stigma, and again when the pollen is ap- plied; butit should not be taken off permanently until the pod or fruit begins to grow. By way of re- capitulation, let us consider the cross- ee ing of a fuchsia Fic. 17.—Fuchsia flower tied up after flower. In Fig. 15 » emasculation. two flowers are shown in full bloom, with the long style and the eight shorter stamens. The single BAGGING THE FLOWER. Bon bud is just the right age to emasculate. We therefore cut off the two flowers and emasculate the bud, as in Fig. 16. The pollen of another flower is applied and the bag is tied on, as seen in Fig. 17. The best label is a small merchandise tag, and this records the staminate parent and the date. It will be seen that in the operation of emascu- lating the fuchsia flower we cut off the sepals as Fic. 18. — Tomato and quince, showing how the sepals were cut off in emasculating. well as the petals. In some plants the calyx adheres to the full-grown fruit, as on the apple, pear, quince, gooseberry, or persists at the base of the fruit, as in the tomato, pea, raspberry. In these fruits, therefore, the cutting away of the calyx leaves an indelible mark which at once dis- tinguishes the fruits which have been crossed, 356 POLLINATION. even if the labels are lost. In Fig. 18 a tomato and quince are shown which are thus marked. All the foregoing remarks do not apply to the crossing of ferns, lycopods, and the like, because these plants have no flowers; yet cross-fertiliza- tion may take place in them. When the spores Fic. 19.— Pollinating kit. of these flowerless plants are sown, a thin green tissue, or prothallus, appears and spreads over the ground. In this tissue the separate sex-organs appear, and after fecundation takes place, the fern, as we commonly understand it, springs forth. Thereafter, this fern lives an asexual life and IMPLEMENTS USED IN CROSSING. ayy produces spores year after year; but it is only in this primitive prothallic stage that fertilization takes place, once in the lifetime of the plant. If these plants are to be crossed, the only procedure open to the gardener is to sow the spores of the intended parents together in the hope that a nat: ural mixing may take place. There are various well-authenticated fern hybrids. The pollination of flowers is such a simple work that few implements are required for its easy performance. Great care is more important than aa Fig. 20. — Pollinating kit. any number of tools. Every one who expects to cross plants should provide himself with the three instruments shown in Fig. 12,—a pin scalpel, sharp-pointed scissors, and a large hand-lens. If one contemplates much experimenting in this direction, however, it is economy of time to have some sort of a box in which there are compart- ments for the various necessities. These various compartments suggest at once whatever accesso- ries are wanting, and they hold a sufficient supply 358 POLLINATION. for several hundred operations. There should be a compartment for bags, string, lens, scissors, and pencils, tags, note-book, and the like. Figs. 19 and 20 show a convenient case for an experimenter, and one which I have used with satisfaction for several years. This kit is twelve inches long, nine inches wide, and three inches deep. TT Pe Since the above advice was written, much has been said on the subject of methods of pollination. Some of the literature is mentioned in the bibli- ography at the end of the book. The reader should consult Charles P. Hartley, ‘“ Injurious Effects of Premature Pollination,” Bulletin 22, Bureau of Plant Industry, United States De- partment of Agriculture, 1902. GLOSSARY. 1. THE FLOWER. Anther. —'That part of the stamen which bears the pol- len. It is the uppermost extremity of the stamen. Calyx.— The outer series of floral envelopes, usually green. The various separate parts of the calyx are sepals. Corolla. — The inner series of floral envelopes, usually colored and forming the showy part of the flower. If — it is divided into separate parts, these are called petals. Essential organs. —'The stamens and pistils. Female. — Said of flowers which have only pistils or the seed-bearing part, or of plants which bear only such flowers; applied also to the pistils in any flower. Filament.— The stalk or stem of a stamen, bearing the anther. Floral envelopes. — The calyx and corolla. Male. — Said of flowers which bear only stamens, or of plants which have only staminate flowers; also applied to the stamens or pollen-bearing organs of flowers. Ovary.— The lowest part of the pistil, containing the ovules. It is the most thickened portion of the pistil, and it may stand either below or above the petals. The ovary ripens into the fruit. Ovule. — A body in the ovary which ripens into a seed. Pet'-al. — The separate parts or leaves of the corolla. Pistil. — The seed-bearing organ of the flower. It always comprises two parts, the ovary — which becomes the pod or fruit—and the stigma. Usually there is a 359 360 GLOSSARY. style connecting the two. Often called the fertile or female organ. Pistillate. — Said of a plant or flower that has only pistils or seed-bearing organs. Pollen.— The contents of the anther, capable of fertil- izing the forming ovules. It is usually composed of minute yellow or brown grains or spores. Se’-pal. — The separate portions or leaves of the calyx. Spore. — A reproductive body, sometimes asexual, by means of which “flowerless plants” propagate; also pollen-grains and embryo-sacs. Stamen. — The pollen-bearing organ of the flower. Often called the male or sterile organ. Its essential part is the anther. The stalk, when present, is called the ~ filament. Staminate. —Said of a plant or flower that bears only stamens or pollen-bearing organs. Stigma. — The top end of the pistil, where the pollen lodges and germinates. It is usually a somewhat ex- panded surface, and is roughened, or sticky, or moist when ready to receive the pollen. Style. — The more or less slender portion of the pistil which lies between the stigma and ovary. The pol- len-tubes pass through it in reaching the ovary. 2. CROSSING. Bigener ; bigeneric-hybrid. — A hybrid between species of different genera. Bigeneric half-breed.— The product of a cross between varieties of species of different genera. Close-fertilization ; self-fertilization. — The action of pollen upon the pistil of the same flower. Close-pollination ; self-pollination. — The transfer of pollen to a pistil of the same flower. Cross. — The offspring of any two flowers which have been cross-fertilized. GLOSSARY. 361 Cross-breed ; half-breed ; mongrel. — A cross between varie- ties of the same species. Cross-fertilization. — The action of pollen upon the pistil of another flower of the same species. Crossing. — The operation or practice of cross-pollinating. Cross-pollination. — The conveyance of pollen to the _ stigma of another flower. Derivative- or derivation-hybrid ; secondary-hybrid. — A hy- brid between hybrids, or between a hybrid and one of its parents. Fertilization ; fecundation ; impregnation. — The action of the pollen upon the forming ovules. Half-hybrid.— The product of a cross between a species and a variety of another species. Hybrid. — The offspring of crossed plants of different species. (See page 284.) Hybridism ; hybridity. — The state, quality, or condition of being a hybrid. Hybridization.— The state or condition of being hybrid- ized, or the process or act of hybridizing. Hybridizing.— The operation or practice of crossing be- tween species. Individual cross. — The offspring of two crossed flowers on the same plant. Individual fertilization. — Fertilization between flowers upon the same plant. Mongrel. — A cross. Mule. — A sterile (seedless) hybrid. Pollination. — The conveyance of pollen from the anther to the stigma (page 252). The term cross is used to denote the offspring of any sexual union between plants, whether of different species or varieties, or even different flowers upon the same plant. It is a general term. And the word is 362 GLOSSARY. also sometimes used to denote the operation of per- forming or bringing about the sexual union. There are different kinds of crosses. One of these is the hybrid. A hybrid is a cross between two species, as a plum and a peach, or a raspberry and a blackberry. There has lately been some objection urged against this term, because it is often impossible to define the limitations of species,— to tell where one species ends and another begins. And it is a fact that this diffi- culty exists, for plants which some botanists regard as mere varieties others regard as distinct species. But the term hybrid is no more inaccurate than the term species, upon which it rests; and, so long as men talk about species, so long have we an equal right to talk about hybrids. Here, as everywhere, terms are mere conveniences, and they seldom express the whole truth. The word hybrid is used in the above sense in this book, with the exception of the new matter now contained in Lecture IV., in which the newer concep- tion is explained. For an explanation of this change in definition, see pages 153, 154. 3. CLASSIFICATION. Break. — A radical departure from the type. Ordinarily used in the sense of sport, but in its larger meaning it refers to the permanent appearance of apparently new or very pronounced characters in a species. Bud-variation.— Variation or departure from a type through the agency of buds (pages 28, 191). Bud-variety. — A variety resulting from bud-variation. Bud-sport. Family (Order in botany.)—A group of genera and species; as Cupulifere, the Oak Family, Rosacee, the Rose Family. Form. — A minor variety, usually transient, produced by some local environment. GLOSSARY. 363 Genus (plural, genera). — A group or kind comprising a greater or less number of closely related species; as Acer, the maples, Fragaria, the strawberries. Mutation.— A term proposed by De Vries to desig- nate the “leaps” or “jumps” whereby species are thought to originate. More definite and specific than “sport.” (See Lecture IV.) Race.— A fixed cultural variety; that is, a cultural va- riety which reproduces itself more or less uniformly from seeds. Seedling. — A plant growing directly from seed, without the intervention of grafts, layers, or cuttings. Seed-variation. — Variation or departure from a type through the agency of seeds. Seed-variety. — A variety resulting from seed-variation. Species (plural also species).— A term used to designate a group of individuals of sufficient distinctness and definiteness to be used as a unit in classification. It is an indefinite term, differently used by different authors. The species-group does not necessarily rep- resent an entity in nature. Sport.— A variety or variation which appears suddenly and unaccountably, either from seeds or buds; some- times, but unnecessarily, restricted to varieties origi- nating from buds, as in this book. Stock. — The parentage of a particular strain or variety. Strain. — A sub-variety, or individuals of a variety, which has been improved and bred under known conditions. Variation.—1. The act or condition of varying or be- coming modified. 2. A transient variety, more or less incapable of being fixed or rendered permanent. Variety.— A form or series of forms of a species marked by characters of less permanence or less importance than are the species themselves. Wilding. — A wild individual from a cultivated species. » x; . BY et heg hak, @ i~ a ees a0 am ‘ : 2 e4 Tee 7 , a%, ae 6 Pr ciate ee BIBLIOGRAPHY. FoLLowine is a list of miscellaneous references to writ- ings on subjects related to plant-breeding. It is not intended to be either complete or comprehensive ; but it is sufficient to give the beginning student a fair conception of the range and extent of the literature, and it will enable him to select writings on specific questions that he may be studying. It has purposely been confined largely to horticultural writings. The literature of cross-fertilization (or cross-pollination) itself —the means by which flowers are pollinated — has been omitted. Those who desire a bibliography of this subject should consult d’Arcy Thompson’s list in Mueller’s “ Fertilization of Flowers.” In the present list I have included many references to the subject of the immediate influence of pollen, although mak- ing no special effort to collect such entries. The proofs have been examined by G. Harold Powell and H. J. Webber of the United States Department of Agriculture, and by W. M. Hays of the University of Minnesota, and others, who have added references. It has not been possible to verify all the added titles. 1724. Dudley, P. An Observation on Indian Corn. Trans. Roy. Phil. Soe. vi. (2), 204-205. 1745. Cooke, Benj. Concerning the Effect which the Farina of the Blossoms of different sorts of Apple trees had on the fruit of aneighboring Tree. Trans. Roy. Phil. Soc. ix. 169. 365 366 BIBLIOGRAPHY. 1748. Cooke, Benj. On a mixed Breed of Apples, from the Mixture of the Farina. Trans. Royal Phil. Soc. ix. 599. 1749. Cooke, Benj. On the Effects of the Mixture of the Farina of Apple trees; and of the Mayze or Indian Corn, etc. Trans. Royal Phil. Soc. ix. 685. 1761. Koelreuter, Joseph Gottlieb. Vorlaiufige Nachricht von einigen das Geschlecht der Pflanzen betreffenden Versuchen und Beobachtungen. 50 pp. Leipzig. Con- tinued in 1763, 1764, and 1766. [Republished in 1893 as No. 41 in Ostwald’s “Klassiker der Exakten Wissen- schaften.” Berlin.] 1793. Sprengel, Christian Konrad. Das entdeckte Geheim- niss der Natur im Bau und in der Befruchtung der Blumen. 444 pp. 25 tab. Berlin. 1806. Knight, Thomas Andrew. Observations on the Means of Producing New and Early Fruits. Trans. Royal Hort. Soc. i. 30. Reprinted in Physiological and Horticultural Papers of Thomas Andrew Knight, 172. 1809. Knight, Thomas Andrew. On the Comparative In- fluence of Male and Female Parents on their Offspring. Trans. Royal Phil. Soc. 1809, pt. i. 392; Phys. and Hort. Papers, 343. 1814. Knight, Thomas Andrew. An Account of two New Varieties of Cherry. Trans. Royal Hort. Soe. ii. 187. 1816. Knight, Thomas Andrew. An Account of three New Peaches. Trans. Royal Hort. Soe. ii. 214. 1817. Knight, Thomas Andrew. An Account of a Peach tree produced from the Seed of the Almond tree, with some Observations on the Origin of the Peach tree. Trans. Royal Hort. Soe. iii. 1. 1818. Herbert, W. Instructions for the Treatment of the Amaryllis longiflora, as a hardy Aquatic, with some Observations on the Production of Hybrid Plants, and BIBLIOGRAPHY. 367 the Treatment of the Bulbs of the Genera Crinum and Amaryllis. Trans. Royal Hort. Soe. iii. 187. 1818. Knight, Thomas Andrew. Upon the Variations of the Red Currant when propagated by Seed [Crosses of white and red currants]. Trans. Royal Hort. Soe. iii. 86. 1818. Knight, Thomas Andrew. Upon the Variations of the Scarlet Strawberry (Frugaria Virginiana) when propa- gated by Seeds. Trans. Royal Hort. Soe. iii. 207. 1818. Knight, Thomas Andrew. Description of a New Seedling Plum. Trans. Royal Hort. Soc. iii. 214. 1818. Sabine, Joseph. Observations on, and Account of, the Species and Varieties of the Genus Dahlia; with In- structions for their Cultivation and Treatment [Refers to Experiments in Crossing]. Trans. Royal Hort. Soc. is 217. 1818. Van Mons, Jean Baptiste. Substance of a Memoir on the Cultivation and Variation of Brussels Sprouts. Trans. Royal Hort. Soc. iii. 197. 1819. Anderson, David. Account of a New Melon, witha Description of the Method by which it was obtained. Trans. Royal Hort. Soc. iv. 318. 1819. Herbert, W. On the Production of Hybrid Vege- tables; with the Result of many Experiments made in the Investigation of the ee Trans. Royal Hort. Soe. iv. 15. 1820. Sabine, Joseph. Account of a Newly Produced Hy- brid Passiflora. Trans. Royal Hort. Soc. iv. 258; also v. 70 (1822). 1820. Turner, John. Observations on the Accidental Inter- mixture of Character of Certain Fruits. Trans. Royal Hort. Soc. v. 63. 1821. Gowen, Robt. On the Production of a Hybrid Ama- ryllis. Trans. Royal Hort. Soc. iv. 498. 1821. Guillemin et Dumas. Observations sur Vhybridité 368 BIBLIOGRAPHY. des Plantes en Général et particulierement sur celle de quelques Gentianes alpines. Mém. Soc. Nat. Hist. Paris, i. 79-92. 1821. Knight, Thomas Andrew. Observations on Hybrids. Trans. Royal Hort. Soc. iv. 367; Phys. and Hort. Papers, 251. 1822. Goss, John. On the Variation in the Color of Peas, occasioned by Cross Impregnation. Trans. Royal Hort. Soc. v. 234. 1823. Gowen, Robt. Description of Amaryllis psittacina- Johnsoni, a New Hybrid Variety raised by William Griffin, Esq., and recently flowered in the Collection at Highclere. Trans. Royal Hort. Soc. v. 361. 1823. Gowen, Robt. Ona Hybrid Amaryllis produced be- tween Amaryllis vittata and Amaryllis regina-vittata. Trans. Royal Hort. Soc. v. 390. 1823. Knight, Thomas Andrew. An Account of some Mule Plants. Trans. Royal Hort. Soc. v. 292; Phys. and Hort. Papers, 275. . 1823. Knight, Thomas Andrew. Some Remarks on the Supposed Influence of the Pollen, in Cross-Breeding, upon the Color of the Seed-Coats of Plants, and the Qualities of their Fruits. Trans. Royal Hort. Soc. y. 377; Phys. and Hort. Papers, 278. 1823. Knight, Thomas Andrew. An Account of a New Variety of Plum, Called the Downton Imperatrice. Trans. Royal Hort. Soc. v. 381. 1823. Lindley, John. A Notice of Certain Seedling Varie- ties of Amaryllis, presented to the Society by the Hon. and Rev. William Herbert, in 1820, which flowered in the Society’s Garden in February, 1823. Trans. a Hort. Soc. v. 337. 1824. Knight, Thomas Andrew. Observations upon the Effects of Age upon Fruit Trees of Different Kinds; with BIBLIOGRAPHY. 369 an Account of some New Varieties of Nectarines. Trans. Royal Hort. Soc. v. 384. 1826. Sageret, Augustin. Considérations sur la production des hybrides, des variantes et des vari¢tés en général, et sur celle de la famille des Cucurbitacées en particular. Ann. Sci. des Nat. Bot. viii. 294-314. 1826. Wiegmann, A. F. Ueber Bastarderzeugung im Pflan- zenreiche. 1827. Hamelin, Baron. On the Hybrids Obtained by Baron Melazzo and others. Annales de la Soc. d’Hort. de Paris, i. No. 2, Oct. Abstr. in Gar. Mag. iii. 443. 1828. Sweet, R. The Permanency of Hybrids. Gar. Mag. iv. 182. 1830. Gowen. Hybrid Azaleas. Edward’s Bot. Reg. 1830, No. viii. 1865, Vol. iv. 1407. Abstr. in Gar. Mag. vii. 62, 471. 1830. Newman, Jno. The Influence of Parent on Off- spring. Gar. Mag. vi. 499. 1831. Hybrid Rhododendron. Brit. Flower Garden, No. xxiii. n.s.91. Abstr. in Gar. Mag. vii. 341. 1831. Hybrid Rhododendrons. Edward’s Bot. Reg. iv. 1413. Abstr. in Gar. Mag. vii. 205. 1831. Lindley, John. Various Notes on Hybridization, in «A Guide to the Orchard and Kitchen-Garden. London, 1831.” Abstr. in Gar. Mag. vii. 579. 1831. Potentilla Russelliana. Bot. Garden, No. lxxvi. 304. Abstr. in Gar. Mag. vii. 348. 1831. Remarks on Hybrids. Florists’ Guide, No. xliv. 174. Abstr. in Gar. Mag. vii. 205. 1831. Saunders, Wm. Hybrid Rhododendron. Gar. Mag. vii. 135. 1832. Dutrochet. The Sterility of Hybrid Plants. Gar. Mag. viii. 500. 1832. Graham, Dr. Hybrid Poppies. Gar. Mag. viii. 355. 370 BIBLIOGRAPHY. 1832. Henslow, J. S. On the Examination of a Hybrid Digitalis. Gar. Mag. viii. 208. Extract from pamphlet. 1832. J.C.K. Hardihood of Hybrid Melons. Gar. Mag. viii. 52. 1832. Mallet, Robert. Hybrid Melons. Gar. Mag. vii. 87. 1832. Oliver, J. A Hybrid of the Cucumber with the Maltese Melon. Gar. Mag. viii. 611. 1832. Wimmer, C. F. H. Ueber einen Bastard aus der Gattung Digitalis. Breslau Schles. Gesell. Uebersicht, 61-62; also 1835, 85. 1835-6. Van Mons, Jean Baptiste. Arbres Fruitiers ou Pomologie Belge Expérimentale et Raisonnée. 2 vols. 12°. Louvain. 1837. (Editorial.) Cabbage and Horse-Radish. Hovey’s Mag. Hort. iii. 351. 1837. Herbert, W. Amaryllidacee, with a Treatise upon Cross-bred Vegetables. London. 1841. Knight, Thomas Andrew. A Selection from the Physiological and Horticultural Papers published in the Transactions of the Royal and Horticultural Societies, by the late Thomas Andrew Knight. To which is added a sketch of his life. 379 pp. London. 1841. Wimmer, C. F.H. Ueber 6 Weidenbastarde. Bres- lau Schles. Gesell. Uebersicht, 93-94. 1843. Wimmer, C. F. H. Ueber die Hybriditat im Pflan- zenreiche. Breslau Schles. Gesell. Uebersicht, 208-209. 1844. (Editorial.) Hybridizing. Gar. Chron. 1844, 459. 1844. Gaertner, Karl Friedrich. Beitrage zur Kenntniss der Befruchtung. 644 pp. Stuttgart. 1844. Godron, D. A. En l’hybridité dans les végétaux. 22 pp. Nancy. 1845. L. Hybrids in Turnips. Gar. Chron. 1845, 173. 1845. Lecoqg, H. Fécondation naturelle et artificiel du végétaux. Paris. Second edition, 1862. BIBLIOGRAPHY. StL 1845. O. Hybrid between a Yellow Picotee and a Red Picotee. Gar. Chron. 1845, 363. 1847. Herbert, W. On Hybridization amongst Vegetables. Journ. London Hort. Soe. ii. 1, 81. 1847. Morton, S.G. Hybrid Plants. Am. Journ. Sci. and Arts, 2 ser. iii. 209. 1847. Wimmer,C.F.H. Ueber die Hybriditat der Weiden. Breslau Schles. Gesell. Uebersicht, 124-131. 1847-8. Regel, E. Ueber Varietiiten und Bastarde im Pflanzenreiche. Mittheil. Ziirich, i. Heft 2, 69-71. 1848. Loiseleur-Deslongchamp. Observations sur les plantes dont les fleurs paraissent de refuser 4 l’Hybridation. Rev. Hort. 3 ser. ii. 149. 1848. Mackenzie, G. S. An Account of Some Hybrid Melons. Journ. London Hort. Soc. iii. 299. 1849. Gaertner, Karl Friedrich. Versuche und Beobach- tungen iber die Bastarderzeugung in Pflanzenreich. 791 pp. Stuttgart. 1849. Lahérard, Jér6me. Raisin précoce Malingre. Rey. Hort. 3 ser. iii. 444. 1849. Pépin. Hybrides des Abutilon striatum et venosum. Rey. Hort. 3 ser. iii. 46. 1849. Wimmer, C. F. H. Uebersicht der bisher bekannt gewordenen Bastarde von Salix. Breslau Schles. Gesell. Uebersicht, 87-93. 1850. Berkeley, M.J. Gaertner’s Observations upon Muling among Plants. Journ. Hort. Soc. v. 156; vi. 1 (1851). ~1850. Naudin,C. Hybridation des Orchidées. Rey. Hort. 3 ser. iv. 9. 1850. Standish and Noble. A Chapter in History of Hy- brid Rhododendrons. Journ. London Hort. Soc. y. 271. 1851. Decaisne, J. Hybridation. Rev. Hort. 3 ser. vy. 62. 1852. Rousselon and others. Sur l’Hybridation. Ann. d’Hort. de Paris, xliii. 35. 372 BIBLIOGRAPHY. 1852. Weddell, H. A. Description d’un cas remarqueble d’hybridité, entre des Orchidées de genres différents. Ann. des Sci. Nat. Bot. 3 ser. xviii. 5. 1853. Grenier, Ch. De l’hybridité et de quelques hybrides en particulier. Ann. des Sci. Nat. Bot. 3 ser. xix. 140. 1853. Malbranche, M. A. De lOrigine des Especes en Botanique, et de l’Apparition des Plantes sur le Globe. 1853. Morren, C. La Fécondation des Céréales. Liege. 1853. Vilmorin, de. The Formation of Races, Varieties and Hybrids in Vegetables. Gard. Jour. (Communicated by A. Henfrey, F.R.S.). Review in Mag. of Hort. 19 (1853), pp. 314-316. 1853. Wimmer, C. F. H. Wild-Wachsende Bastardpflan- zen, hauptsachlich im Schlesien beobachtet. Breslau Schles. Gesell. Denkschr. 143-182. 1854. Klotzsch, J. F. Ueber die Nutzanwendung der Pflanzen-Bastarde und Mischlinge. Berlin. Bericht. pp. 535-562. 1855. (Editorial.) Hybrids Exhibited at the Horticultural Society. Gar. Chron. 1855, 451. 1855. Godron, D. A. De la Fécondation des Zgilops par les Triticum. Nancy. 1855. Klotzsch. Sur l’Utilité des Hybrides. Rev. Hort. 4 ser. iv. 342. 1855. Naudin, C. Hybridation des Cucurbitacées. Rev. Hort. 4 ser. iv. 64. 1855. Naudin, C. Réflexions sur |’Hybridation dans les Végétaux. Rev. Hort. 4 ser. iv. 351. 1855. Regel, E. Zur Agilops Frage. Bot. Zeit. xiii. 569- 573. 1856. Godron, D. A. De l|’#gilops triticoides et de ses differentes Formes. (Mémoir Acad. Stanislas), Nancy. 1856. Gray, Asa. Review of Hooker and Thomson’s Flora Indica, in which Hybridization is discussed in its re- BIBLIOGRAPHY. = Ste lation to Variability. Am. Journ. Sci. and Arts, 2 ser. xxi. 135; reprinted in Scientific Papers of Asa Gray, i. 62. 1856. Naudin, C. Nouvelles recherches sur les charactéres spécifiques et les variétés des plantes du genre Cucurbita. Ann. des Sci. Nat. Bot. 4 ser. vi. 5. Review by Asa Gray in Am. Journ. Sci. and Arts, 2 ser. xxiv. 440; reprinted in Scientific Papers of Asa Gray, i. 83. 1856. Radlkofer, L. Befruchtung der Phanerogamen. Leipzig. 1856. Regel, E. Der Bastard zwischen gilops ovata and Triticum vulgare. Bonplandia, iv. 243-246. 1856. Sanrey, J. DelHybridation. Rev. Hort. 4 ser. v. 223. 1857. Regel, E. Ueber Parthenogenesis und Pflanzen Bas- tarde. Bonplandia, v. 302-305. 1857. Vilmorin, L. de, and J. Groenland. Note sur VHybridation du Genre Agilops. Rey. Hort 193. 1858. Gray, Asa. Action of Foreign Pollen upon the Fruit. Am. Journ. Sci. and Arts, 2 ser. xxv. 122. 1858. Regel, E. Hybridation des Begonia rubrovenia et zanthina. Gartenflora, Jan. 1858. Ext. in Ann. d’Hort. de Paris, iv. 442. 1859. (Editorial.) A Leguminous Hybrid. Gar. Chron. 1859, 71. 1859. Darwin, Charles. Chapter on Hybridism (ix.) in “Origin of Species.” 1859. Saulget,G.du. Résultats de l Hybridation du Cactus (Epiphyllum) Ackermanni. Ann. d’Hort. de Paris, v. 394. 1859. Stange, F. E. Hybrides et formes diverses obtenus par la Fécondation de differents Begonia entre eux. Hamburger Garten- und Blumen-zeitung. March, 1859. Reviewed in Ann. d’Hort. de Paris, v. 295. . 374 BIBLIOGRAPHY. 1859. Vilmorin, L.de. Notices sur ]’Amélioration des plantes par le semis et Considerations sur l’Hérédité dans les Végétaux. Paris. Review by Asa Gray in Am. Journ. Sci. and Arts, 2 ser. xxvii. 440; reprinted in Scientific Papers of Asa Gray, i. 109. 1860. Wylie, Dr. Hybridizing the Peach with the Plum. Gar. Month. ii. 231. 1861. Anderson-Henry, I. Variegation, Cross-Breeding and Muling of Plants. Journ. Hort. xxvii. o. s. 41. 1861. Beaton, D. Cross-Breeding and Hybridizing. Journ. Hort. xxvii. 237. 1861. Beaton, D. Facts and Opinions, Past and Present, rela- tive to Cross-Breeding Plants. Journ. Hort. xxvii. 0.8. 289. 1861. Beaton, D. Phenomena in the Cross-Breeding of Plants. Journ. Hort. xxvi. o. s. 112. 1861. Brent, B. P. Cross-Breeding Sweet-Peas. Journ. Hort. xxvi. o. s. 160. 1861. Carriere, E. A. Quelques mots sur les Hybrides. Rey. Hort. 47. 1861. Darwin, Chas. Cross-Breeding in Plants. Journ. Hort. xxvi. o. s. 151. 1861. Naudin,C. Sur les plantes Hybrides. Rev. Hort. 396. 1861. Smith,Wm. Hybridizing Mangle’s Silver-Bedding Geranium. Journ. Hort. xxvii. o. s. 195. 1861. Wimmer, C. F. H. Ueber Weiden-Bastarde und iiber Salix grandiflora. Breslau Schles. Gesell. Jahresb. xxxix. 100-101. 1862. Beaton, D. Progress of Cross-Breeding among Florists’ Flowers. Journ. Hort. xxvii. o. s. 309. 1862. Caspary, Robt. Ein Bastard von Digitalis purpurea und lutea. Schrift. Phys. Okon. Gesell. Kénigsb. iii. 139-146. 1862. Goeze, Emmanuel. Hybridation du Poa aquatica et du Clyceria fluitans. Rev. Hort. 375. BIBLIOGRAPHY. 375 - 1862. Lecog. See 1845. 1863. Anderson, J. On Orchid Cultivation, Cross-Breeding and Hybridizing. Journ. Hort. 206. 1863. Brongniart, Decaisne, Tulasne, Moquin-Tandon, and Ducharte. Rapport sur la question de |’Hybridité dans les Végétaux, mise an Concours par l’Académie des Sciences en 1861. Ann. des Sci. Nat. Bot. 4 ser. xix. 125. See also Ann. d’Hort. de Paris, ix. 56. 1863. Godron, D. A. Des hybrides Végétaux considérés au point de vue de leur fécondité et de la perpétuité ou non-perpétuité de leurs caractéres. Ann. des Sci. Nat. Bot. 4 ser. xix. 135. 1863. Godron, D. A. Recherches expérimentales sur Vhybridité dans le regne végétal. 76 pp. Nancy. 1863. Naudin, ©. Nouvelles recherches sur l’hybridité dans les végétaux. Ann. des Sci. Nat. Bot. 4 ser. xix. 180. 1864-6. Mares, Henri. De la fécondation des fleurs steriles de la Vigne. Mém. Acad. Sci. Montpellier, vi. pp. 40-42. 1865. Bentham, George. Anniversary Address to the Lin- nan Society. Journ. Linn. Soe. viii. pp. xi.-xxiil. 1865. Carriere, E. A. Production et Fixation des ae dans les végétaux. 72 pp. Paris. 1865. Déy. Lettres sur la fécondation artificielle des plantes. Vesoul. 1865. (Editorial.) Is the Quality of Fruit Changed by Hybridizing? Gar. Month. vii. 304; vol. viii. 144. 1865. Gray, Asa. Spontaneous Return of Hybrid Plants to their Parental Forms [Note upon the essays of Naudin and Godron]. Am. Journ. Sci. and Arts, 2 ser. xxxix. 107. 1865. McNabb. Will Pines Hybridize? Gar. Month. vii. 318. 1865. Mendel,G. Versuche iiber os ana Brinn Verhandl. iv. 3-47. 376 BIBLIOGRAPHY. 1865. M.J.B. Variation in Hybrids. Gar. Chron. 1865, - 601. 1865. Nigeli, Karl. Die Bastardbildung im Pflanzenreiche. Sitzungsber. der Kongl-bayer. Akad. der Wissensch. zu Miinchen, ii. 395-445. 1865. Sagot. De l'état sauvage et des résultat de la culture et de la domestication. Nantes, 1865. 1865. Scott, John. Notes on the Sterility and Hybridiza- tion of Certain Species of Passiflora, Disemma, and Tac- sonia. Journ. Linn. Soc. Bot. viii. pp. 197-206. 1865. Verlot, J. B. Sur la production des Variétés. 102 pp. Paris. 1865. Wichura, Max. Die Bastard-befruchtung im Pflan- zenreich erlaiutert an den Bastarden der Weiden. 95 pp. 2 tab. Breslau. 1866. Godron, D. A. Nouvelles recherches sur l’Hybridité dans le regne végétal. 40 pp. Nancy. 1866. Neumann, L. Phénoméne d’hybridation observé dans le genre Mathiola. Rev. Hort. 286. 1866. Standish, J. Hybridizing Fruits. Gar. Chron. 1866, 109. Also Gar. Month. ix. 284. 1866. Stayman, J. Is the Quality of Fruit Changed by Hybridization? Gar. Month. viii. 101. 1867. Anderson-Henry, I. The Hybridization of Plants. Gar. Month. ix, 379. 1867. Anderson-Henry, I. On Pure Hybridization, or Crossing Distinct Species of Plants. Gar. Chron. 1867, 1296, 1313. 1867. Braun, A. Rejuvenescence, Especially in Mosses and Ferns. Gar. Month. ix. 147. 1867. Crucknell, Chas. Does Hybridizing Change the Fruit as well as its Progeny? Gar. Month. ix. 165. 1867. (Editorial.) Hybridization. Gar. Chron. 1867, 403. 1867. Hildebrand, F. Die Geschlechtsvertheilung bei den BIBLIOGRAPHY. ott Pflanzen und das Gesetz der Vermiedenen und unvortheil- haften stetigen Selbstbefruchtung. 92 pp., 62 fig. 1867. Mares, H., and J. Planchon. Sur la floraison et la fructification de le vigne. Comp. Rend. lxiv. pp. 254-259. Translation in Ann. and Mag. Nat. Hist. 3 ser. xix. pp. 220-224. 1867. Nigeli, K. Intermediate Forms in Plants. Gar. Chron. 1867, 405. 1867. R.D. Hybrid Tropzolums. Gar. Chron. 1867, 906. 1867. Rivers, Thos. Hybridizing and Cross-Breeding. Gar. Chron. 1867, 516. 1867. Stelzner. The Hybridization of Ferns. Gar. Month. ix. 60. 1868. Darwin, Chas. Chapters xv.-xix. of “Variation of Animals and Plants under Domestication.” 1868. (Editorial.) Hybrid Coleuses. Gar. Chron. 1868, 1210. ; 1868. Hildebrand, F. Ueber die Einfluss des fremden Pollens auf die Beschaffenheit der durch ihn erzeugten Frucht. Leipzig. 1868. Moore, Jacob. Grape Hybrids. Gar. Month. x. 240. 1868. St. Pierre, M. G. de. Hybridization of the Gourd. Gar. Chron. 1868, 681. 1868. Tidey, A. Effect of Cross-Imprégnation on Seeds. Journ. Hort. xxxix. o. s. 199. 1868. T.M. New Hybrids of Coleus. Gar. Chron. 1868, 376. 1868. Wylie, A. P. Hybrid Grapes. Gar. Month. x. 153. 1869. Darwin, Chas. On the Character and Hybrid-like Nature of the Offspring from the Illegitimate Unions of Dimorphic and Trimorphic Plants. Journ. Linn. Soc. Bot. x. pp. 3893-487. 1869. Darwin, Chas. On the Specific Differences be- tween Primula veris, P. vulgaris, and P. elatior; and on 378 BIBLIOGRAPHY. the Hybrid Nature of the Common Oxlip. With Supple- mentary Remarks on Naturally-produced Hybrids in the Genus Verbascum. Journ. Linn. Soc. Bot. x. pp. 437-454. 1869. Mendel, G. Ueber einige aus Kiinstlicher Befruch- tung Gewonnenen Hieracium-Bastarde. 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