INTRAVARIETAL CROSSING AND MENDEL'S SO-CALLED "LAW" OF SEGREGATION1
T. D. Lysenko
|1 Revised stenographic report of a lecture delivered on April 15, 1938, at a seminar on seed growing at the All-Union Institute of Selection and Genetics—Ed.|
THE MAIN thing in the problem of seed growing is knowledge and ability to grow good seeds of the crop with which the particular seed grower is working. The science of seed growing must not be regarded as an appendage of genetics and plant breeding, a many have been and still are inclined to do. Actually seed growing is one of the major departments of agronomic science, and includes all the other branches of science that deal with the life and development of plants.
In the first place, seed growing includes that branch of science which studies the laws of variability and heredity, i.e., genetics. Seed growing also includes agrotechnique, which deals with the conditions that must be created to grow seeds of a definite quality. Also included is plant breeding, which deals with the selection of plants for breeding, and with the time and manner in which they should be selected. In addition to all this, seed growing has something specifically its own. In general, seed growing is one of the major departments of agronomic science and not an appendage of genetics and plant breeding.
Seed growing does not emerge from the tenets of genetics which in many respects are fictitious. On the contrary, the requirements of seed growing have given rise to the genuine branches of science known as genetics, plant breeding and agrotechnique (the creation of prerequisite conditions for cultivating plants for seeds).
The theoretical basis of seed growing, as of every other department of agronomic science, must be the theory of development. In this article I shall deal with only one of the numerous problems concerning the production of seeds, namely, the theoretical basis of the problem of intravarietal crossing.
During the whole period of over two years that the problem of intravarietal crossing has been studied it has always been connected with Darwin's theory. And this problem has been connected with Darwin's theory not only by us, who advanced the problem and urge that the periodical cross-pollination of self-pollinating field crops is beneficial, but also by our opponents in matters of theory, who deny that such crossing is beneficial.
Why do people who hold diametrically opposite views appeal in the present case to the same theory, to Darwinism? The following answer may be given: having unsuccessfully tried to challenge Darwin's principles, the opponents of Darwinism are now trying to lean on Darwin's utterances.
We proceed from the proposition that long-continued self-pollination is biologically harmful because the plants become less fit, less viable, less resistant to unfavourable climatic, soil and other conditions and, following Darwin, we assert that cross-pollination is beneficial.
Our opponents, however, the representatives of the Mendel-Morgan school of genetics, who formerly totally denied the usefulness of even raising this problem, now say: cross-pollination is biologically beneficial only for cross-pollinating plants; self-pollinators benefit from cross-pollination only when the self-pollinator constitutes a population and not an ordinary pure line. Thus, the practical importance of the problem of intravarietal crossing is again reduced to zero.
I repeat—we have proceeded and continue to proceed from the proposition that intravarietal crossing is never harmful and will always he biologically beneficial to some extent. As regards field crops this, as a rule, will coincide with economic utility.
What prevents those who advocate Morganist genetics from appreciating the good of crossing and the harm of self-pollination? This question may be briefly answered as follows: they are prevented by the principle on which the theory they advocate is built; they are prevented by their wrong conception of the nature of living organisms.
The Morganists picture the heredity of organisms as some sort of special substance. This substance, like every other, they divide into discrete particles, or granules. The point is, however, that "hereditary substance" is an invention of the Morganists; it does not exist in nature. As is known, the Morganists have placed this fictitious hereditary substance in the chromosomes of the cell nuclei in a linear, catenulate arrangement. They have endowed these particles of heredity with a property that not a single molecule of the living organism possesses, namely, the property of not developing, of not undergoing transformation. To put it more simply, they have ascribed to these fictitious particles of heredity some sort of miraculous property of growing, of propagating in billions, and at the same time of not undergoing change. But we know that we cannot picture a single living organism, not a single part of an organism, as growing and propagating, and yet not undergoing change and transformation. If there is no change, no transformation, it goes without saying that there is no development.
This is exactly why seed growers and plant breeders who believe in the principles of the Mendel-Morgan theory assert that the hereditary basis of all the organisms which in the past, 10 to 15 years ago, were obtained from one initial seed has remained unchanged. Hence their view that it is useless to cross such plants.
As regards pure-line varieties, in the opinion of geneticists the harm of self-pollination and the good of cross-pollination have been disproved beyond all question.
The inbreeding of cross-pollinating plants, now proved to be a wrong method, is based on the theory of Morganism. Plants obtained by inbreeding are always feeble, of low resistance and, as a rule, less productive. The explanation of this, given by the Morganists in the past and even to this day, is that the failure of inbreeding is due not to consanguineous breeding, as the Darwinists think, but to the fact that closely-related breeding leads to the homozygosity of bad genes (accumulation of bad hereditary particles) which were screened by other, dominant genes, when the organism was in the heterozygous state.
|1 "If evil is brought to light, inbreeding is no more to be blamed than the detective who unearths a crime. Instead of being condemned it should be commended." (Edward M: East and Donald F. Jones, Inbreeding and Outbreeding, Their Genetic and Sociological Significance, Philadelphia and London 1919, p. 140.)|
D. F. Jones compares inbreeding to the work of a skilful detective and in effect says the following: Who will condemn the useful work of a detective if he unearths a wicked crime? But inbreeding is condemned by the ignorant who fail to understand that it really ought to be commended. Inbreeding merely reveals to us the bad genes that existed in the given variety but did not manifest themselves. The variety grew splendidly for scores of years, but you did not know that bad genes were hidden in it, and it is only due to inbreeding that the "criminals" were discovered. Were it not for inbreeding you, perhaps, would never know that the variety of plant from which your breed is made contains such evil things as hidden genes.1
This is what one can arrive at in the department of seed growing if Morganism is taken seriously for practical purposes, or if it is taken seriously, without a smile, as a science.
We Darwinists hold different views. We proceed from the proposition that the conditions of life, the conditions of training a plant organism, are in some degree reflected in the behaviour of the plant's progeny. No two things in the world are absolutely alike, and no two square metres of field are alike. Hence, environmental conditions are always in some degree different for different plants. For this reason alone—and it is not the only one, of course—it is never possible to picture even two plants of the purest variety as being absolutely alike in morphology or in their nature, i.e., their hereditary basis.
Plants propagate their kind in the most diverse ways, but principally by means of sexual reproduction.
What is the principal specific feature of sexual reproduction? With sexual reproduction the organism starts life anew. Organisms which, in contradistinction, are not obtained from sex cells, but from cuttings, tubers, bulbs, etc., do not start life anew, but continue it. It is widely known that to sow seeds of, for example, winter wheat in spring it is necessary to vernalize them, i.e., to put them under conditions that will enable them to go through the vernalization phase. If, however, cuttings are taken from the fruiting parts of the plants of the very same wheat, there is no need to put them under conditions required for vernalization. If the plant is already phasically mature, and if cuttings are taken from its top, there is no need to put them under conditions for going through the vernalization phase, or the photo phase.
Sexual reproduction differs fundamentally from every other mode of propagation precisely in the fact that, in the former, the life of the organism starts anew, whereas in vegetative reproduction life continues. This, I think, contains the answer to the question why natural selection created the sexual mode of reproduction, why there are two sexes in animals and in plants. From the Darwinist standpoint this question can be answered fairly easily.
Organisms always possess the property of traversing the same path of development that their ancestors did, but since the environmental conditions of a given plant are never absolutely like those of its ancestors, the heredity of the seeds is never absolutely like that of the seeds of the preceding generations. This is precisely how a new heredity is created by the alteration of the old.
|1It is known that organisms can develop from unfertilized sex cells, but from time to time, these species of organisms also resort to fertilization.|
Two sex cells fuse during fertilization and produce one cell (the zygote)—the beginning of the organism. This new, enriched cell produces an organism more adapted for development than it would have been had it developed from each separate unfertilized cell.1
It must be emphasized that upon fertilization, i.e., when two cells fuse, a third cell is obtained—the zygote—which is not only better adapted to the conditions of development than either of the sex cells, but is more viable. We will observe, in passing, that greater viability and greater adaptability to the given environmental conditions are not the same thing
Why, then, does long-continued self-pollination lead to the waning, the enfeeblement of life, and we get what is called degeneration? Up till now we have given only one explanation of this: the shrinking of the range of potentialities of adaptation to environmental conditions. This is true, but it is not the only reason. Probably this is not the chief benefit derived from cross-pollination. If the blood is not renewed, refreshed, by crossing after long-continued self-pollination, the viability of the progeny diminishes, wanes. With this, the adaptive potentialities of development possessed by the progeny also diminish.
|1 True, the point here is not that the eyes of such investigators are imperfect, but that their mode of thinking prevents their eyes from seeing what can and should be seen.|
|2 "It should be remembered," wrote Darwin, "that in two of the cases, in which highly self-fertile varieties appeared amongst my experimental plants, namely, with Mimulus and Nicotiana, such varieties were greatly benefited by a cross with a fresh stock or with a slightly different variety; and this likewise was the case with the cultivated varieties of Pisum sativum"… "By the term fresh stock I mean a non-related plant, the progenitors of which have been raised during some generations in another garden, and have consequently been exposed to somewhat different conditions."… If the flowers are not visited by our native insects, or very rarely so, as in the case of the common and sweet pea, and apparently in that of the tobacco when kept in a hot house, any differentiation in the sexual elements caused by intercrosses will tend to disappear. This appears to have occurred with the plants just mentioned, for they were not benefited by being crossed one with another, though they were greatly benefited by a cross with a fresh stock." (My italics.T. L.) (Ch. Darwin, The Effects of Cross and Self Fertilization in the Vegetable Kingdom, Second Edition, London 1878, pp. 389, 257, 458.)|
An opponent of the theory of intravarietal crossing may say, or think: "All this is true, I do not dispute this, but alter all, within the limits of a pure variety the heredity of the plants is the same. It may not be the same from the standpoint of dialectical materialism, but in the seed nursery my own eyes convince me that it is the same."1 And here the opponent of the theory of intravarietal crossing will not fail to mention Darwin, and argue that Darwin himself said that crossing was beneficial only when the organisms taken for crossing differed, if only slightly, in their hereditary natures. Even in Darwin's experiments, he will say, no benefit was derived from crossing when the hereditary natures were the same; and he will quote examples to show that the crossing of peas of one variety performed by Darwin produced no effect.
In citing these examples, however, the opponents of intravarietal crossing juggle with the facts: they misrepresent Darwin's experiments. Darwin proved the very opposite, namely, that if pea plants are taken for the purpose of uniting by cross-pollination and if the preceding generations of these plants had developed even under slightly different conditions, there will be a fairly considerable increase in the viability, the vigour, of the progeny.2
Here the following question may at once arise: on a collective farm the plants of a pure variety grow in one field, but Darwin says that cross-pollination is beneficial only when the plants of the preceding generations were grown in different gardens and had, consequently, been exposed to somewhat different conditions. We may be told that the plants of every one of the pure lines of winter wheat (even such as Hostianum 0237, or the varieties bred by L. P. Maximchuk: Od-01, Od-02, Od-03) have the same heredity. It is a fact that in seed nurseries small plots are usually planted with the progeny of separate specimens typical of the variety, and the plants on all these plots are always homogeneous. Only in rare exceptions has it been observed that the plants on one plot deviate somewhat from the type, and this is usually attributed not to a difference between the heredity of these plants and that of the plants on the other plots, but to a difference in the field conditions, to differences in microrelief. Since such an ideal homogeneity is observed in the seed nursery, it would seem to follow, according to Darwin's theory, that it is useless to cross-pollinate plants belonging to pure-line varieties of wheat.
The point, however, is that this reference to seed nurseries is unconvincing as far as we are concerned, if only for the reason that people who talk like this usually have had little to do with examining plants and still less with planting nurseries. They know about them only from books. And in many cases, books on various departments of agronomic science are unfortunately written by people who have no practical knowledge of the subject.
Most of the propositions advanced in agronomic science are of such a nature that not only is it unwise to insist upon them for long, but the investigator should himself try to "undermine" them, even though he himself has advanced them. Such propositions may be relatively correct, effective, and therefore useful; nevertheless, more effective and more correct propositions must be found to replace them. But there are certain propositions which must be understood, always remembered and used as the point of departure in one's work. They must never be deviated from or their correctness doubted. These propositions are the fundamental concepts of the theory of development, the principles of dialectical materialism.
According to dialectics, every identity, every sameness always contains differences. Hence we cannot imagine two offsprings of a plant being in no way different from each other.
We cannot imagine that 200 to 300 plants taken from a large mass. of a line, however pure, should produce progeny that are absolutely alike. In some way the offspring will differ from each other.
In most cases, the difficulty in revealing these differences among the progenies of pure lines lies in the lack of experience (the untrained eye, as they say) of many scientists in perceiving differences among the progenies of crops in seed nurseries. This is one reason. The chief difficulty, however, is often the wrong approach to the technique of planting and tending seed nurseries.
How are seed nurseries of winter wheat usually planted? From 20 to 40 seeds are sown from each plant chosen. The space between the plants in a row is 5 cm., and between the rows 15 cm. This mode of planting does not preclude the possibility that among 10,000 offspring of Ukrainka winter wheat the seed grower will fail to see, until earing, even one or two offspring of barley that had got mixed up with the crop. The plants on the plots will spread out like a single carpet, all will look alike, and it will be impossible to distinguish the Ukrainka plants on one plot from the Ukrainka plants on another plot, i.e., from another progeny.
This can be very vividly and practically illustrated on the experimental plots at the Institute of Selection and Genetics.
Plants known to be hybrid (second-generation Krymka x Ukrainka) were taken and their seeds planted in separate families, i.e., seeds from each plant were sown on a separate plot. Technique of planting: grain from grain 5 x 15 cm. From every plant 1,000 grains were planted instead of the usual 20 or 40.
Another nursery was planted with seeds from the parents that had been picked as typical of the varieties Krymka, Hostianum 0237, Od-01, Od-02 and Od-03. The planting was different from that in the first nursery: the space between grains in a row was 25 cm., and between rows 70 cm. Length of plot—100 m. On each plot 1,200 grains were planted.
According to the geneticists there should be a diversity of plants on these nursery plots (second generation Krymka x Ukrainka); but it is difficult and in many cases impossible, at least today, for us to see differences in the plants on the same hybrid plots. On the other hand, on the plots in the second nursery, where, according to the geneticists, there should be no diversity, differences between the progeny of one family and the progeny of other families of the same pure-line variety can easily be seen. Let us note here that for planting this second nursery only spikes that were typical of the variety, i.e., of 100% purity, were taken.
Such planting of a nursery clearly reveals that intravarietal cross-pollination among our pure-line winter wheats does not contradict Darwin's theory, but, on the contrary, is based on it and confirms it; for slight differences in the plants of the pure-line varieties are observed, and this ensures a favourable result of the intravarietal crossing.
When Darwin crossed pea plants growing in one or two pots, in which, of course, the conditions were in very many ways identical, there was no increase in the vigour of the progeny. But when he crossed plants which, although growing in one pot, were of different origin (the seeds had been grown by different owners in different gardens), the results, as is known, were good as regards increase in the vigour of the progeny.
On large collective- or state-farm fields, the plants of pure-line varieties, of course, encounter conditions no less diverse than those obtaining for pea plants of the same variety but grown in different neighbouring gardens. And it was the latter that Darwin used for his experiments, which gave such brilliant results. As regards the environmental conditions of any pot in which plants are grown, they are immeasurably less diverse than those on large collective- or state-farm fields.
Thus, the attempt of the opponents of intravarietal crossing to lean on Darwin in their assertion that intravarietal crossing should not be performed with pure-line varieties fails utterly, because Darwin's experiments with the peas, for instance, and with other self-pollinators point to the beneficial influence of intravarietal crossing. The seeds of pure-line varieties of winter wheat certified by the experts to be 100% pure, are, as a rule, sufficiently heterogeneous in their hereditary natures to renew, refresh, the blood of the progeny as a result of cross-pollination.
In the winter-wheat seed nurseries at the Institute of Selection and Genetics, another extremely important principle that follows from Darwinism may he seen in operation. We have nurseries with progeny from plants of the same varieties of winter wheat that had not been subjected to intravarietal crossing, and progeny (F2) taken from first-generation plants after intravarietal crossing. In these nurseries it may easily be observed that intravarietal crossing does not increase diversity among the plants, does not disturb the typicalness of the variety. True, it was evident to us without this that crossing does not increase but eliminates diversity in the outer appearance of the population, and this makes the variety more uniform.
But the most important and interesting thing about the phenomena observed in these nurseries at the present time, particularly with regard to the Krymka variety, is that here we find clearly revealed the fundamental error committed by the Mendelists and Morganists on the question of the diversity (segregation) of hybrids in the second generation.
The geneticists assert that the unshakeable foundation of their entire theory is the law, discovered by Mendel, that hybrid progeny must without fail segregate. In the paper he read at the session of the Academy of Agricultural Sciences in December 1936, Academician Serebrovsky said: "The first cardinal fact is that in crossing the progeny segregates according to given characters into groups which are multiples of each other. This law of multiple relation was discovered by Mendel (1865) and the whole edifice of present-day genetics is built on it ...."
According to the theory of the geneticists, as everybody knows very well, firstly, the progeny of every hybrid segregates according to the characters of the father or the mother; secondly, Mendel's segregation, to which, in the opinion of the Morganist geneticists, hybrids of peas, wheat, trees, animals, and all other living things on earth in general are subject, requires that diversity of the progeny should always he in the ratio of 3:1. For every three specimens of progeny possessing the characters of the father or the mother, there must be one which possesses the opposite characters.
For the geneticists, this principle is indeed unshakeable, because the entire edifice of Mendelist-Morganist genetics is built on it. But this, of course, does not mean that segregations in the multiple relation of 3:1, or the derivative of three to one (3:1)n, on which genetics is based, is correct. Obviously, it contradicts the fundamental thesis of dialectical materialism. To assume that the hybrid progeny of all varieties of wheat, peas and of various other plants and animals must "segregate" in the same way and in an equal degree means totally ignoring biology, failure to take the environment into account. Can the immense diversity of living nature be forced into the narrow and rigid scheme of 3:1 ?!
Unfortunately, not only have the Morganist geneticists tried to do this in their own department of science, but they have rammed this idea fairly strongly into the minds of our plant breeders, seed growers, and of all of us agronomists. Actually, I do not think that anybody has seen diversity in the plants of hybrid progeny always being in the ratio of 3:1, that for every three specimens of a particular character there should always be one of the opposite character. Even in Mendel's own experiments not a single hybrid pea plant produced progeny with a diversity of colour of flower, or colour of seed, in the ratio of 3:1. It is enough to study the records of Mendel's experiments to find out without much difficulty that even in the progenies of the 10 hybrid plants of peas given in Mendel's tables, the progeny of one plant had 19 yellow seeds to 20 green ones, while that of another plant had 33 yellows to only one green. In the progenies of different plants of the same hybrid combination, different ratios of types were observed. The possibility is not precluded, of course, that diversity in the progeny of a given plant will be in the ratio of 3:1, but this will be as frequent, or a rare, as the ratios 4:1, 5:1, 50:1, 200:1, and so forth. On the average, of course (not always, by any means), the ratio may be 3:1; but this average ratio of three to one is obtained, and the geneticists obtain it (this they do not deny) from the law of probability, from the law of large numbers. It is common knowledge that the most widespread method of explaining this "biological law" in classes on genetics is the tossing of two coins. Students are asked to assume that the coins are sex cells (of peas, say) and to register, every time the coins are tossed, how many times the two fall tails up, how many times the two fall heads up, and how many times one falls tail up and one head up. They are advised to toss the coins as many times as possible. With a large number of tossings the result is approximately as follows: in 25% of the total number of tossings both coins fall head up, in 25% tail up, and in 50% one head and one tail up, i.e., in the ratio of 1:2:1.
The development of hybrid plants always proceeds in that of all the possible directions for which the conditions of the given field are most suitable. In the development of hybrid organisms, one or other potentiality of the given organism always gains a developmental advantage. The geneticists say that if heads (we will assume that this means red pea flowers) are dominant, i.e., gain the advantage, then all the organisms that come from the fusion of two sex cells, one of which had the potentiality of developing red flowers and the other white, will develop red flowers. According to the "biological" test of coin tossing, the proportion of red-flower plants will be 50% and 25% where both sex cells possessed the potentiality of developing red flowers; total, 75% red flowers and 25% white, i.e., a ratio of 3:1. The geneticists are firmly convinced that this must be the case among all the offspring of hybrids in the whole of living nature, no matter where and how they were crossed and grown. Actually, of course, this is far from inherent in the whole of living nature. It is not even inherent in the hybrid peas from which this "pea law," as I. V. Michurin aptly called it, was deduced.
In short, there is as much in common between biological law and "Mendel's law" as there is between a penny and a pea plant.
After closely observing the behaviour of the plants in winter-wheat seed nurseries, and especially those of Krymka obtained from intravarietal crossing, I boldly assert that nobody has ever seen the hybrid progeny of different plants of the same combination all vary in the same ratio (3:1)n. Such a ratio may be obtained only if coins are tossed a large number of times, or in any other case where only equal probability based on chance plays a role, where necessity is averaged.
A close examination of the Krymka seed nurseries planted in the field where the progeny of seeds from typical Krymka spikes were growing revealed to me that the variety presented such a heterogeneous population that it was literally impossible to point to two offspring that were exactly alike. Of the relative uniformity that people are accustomed to see in this variety there was not even a trace in this case. The wheat plants, still in the grass form (there is no earing yet) differed sharply according to families (lines). At the same time, one could feel confident that after earing, ripening and harvesting, the morphology of the spikes in all these families taken together would constitute 100% pure variety according to experts' standards. After all, the seed-growing experts had chosen only typical spikes for planting in the nursery; nontypical spikes, so-called admixtures (red spikes with tinted awns, or awnless spikes), were not taken when plants were selected for the seed nursery; they were culled.
Seeing this sharp difference between some of the progenies of Krymka and others, and knowing, furthermore, that this great diversity appeared after the variety had been purged of nontypical admixtures, I asked myself: what may one expect, according to the theory of genetics, if several thousand spikes indiscriminately chosen from the Krymka population not purged of admixtures are castrated and left to be freely pollinated by the wind? In the first generation, according to Mendelism, there should be a diversity of plants, since both fathers and mothers differ relatively sharply from each other, and F1 of many combinations is present.
In 1937 we did observe this diversity in such a first-generation nursery. True, this diversity was less than that of the Krymka which had not been subjected to intravarietal crossing. Every plant of the first generation of the Krymka variety was a hybrid of the parent forms, morphologically differing sharply in vigour, colour of leaf, shape of tuft and other characters.
According to Mendelism and Morganism, in the second generation, the progeny of every such plant should be diverse. That is to say, if intravarietal crossing is performed in the population of a given variety it is impossible, according to genetics, to release uniform seed within the next two or three years. If the slightest faith can be put in the relative truth of Mendelism-Morganism, then, after seeing the seed nursery of our Krymka, where the progeny of separate plants had been planted, it would be a risky thing to perform intravarietal crossing in such a population. Unfortunately, until quite recently I too still believed that hybrids obtained from morphologically different parents must unfailingly show diversity in the succeeding generations, even if not in the ratio of (3:l)n.
But what do we see now on the six hectare Krymka nursery among the second-generation plants obtained from the intravarietal crossing? The diversity among the progenies (we planted 1,200 grains of each line) of the different plants is fairly considerable, but less and not greater than the diversity in the Krymka nursery where there had been no intravarietal crossing. The main thing, and for me the most important, is that for the first time I saw with my own eyes a numerous progeny of plants known to be second-generation hybrids as homogeneous as the progeny of ordinary nonhybrid wheat plants. In this nursery numerous cases can now be seen where there is no segregation in the second hybrid generation of wheat.
It is not difficult to perceive how much we seed growers and plant breeders were hindered by the geneticists' tenet that had been dinned into our ears, that all the progeny of hybrid plants must under all conditions show diversity, i.e., "segregation." On this principle plant breeders, as a rule, mixed the seeds of different plants of the first hybrid generation. The planting of the second hybrid generation was not done with the progeny of each separate plant of the first generation, but a mechanical mixture was made of the different progenies of the same hybrid combination, thus hindering the selection of constant desirable le plants in succeeding generations.
Judging by the seed nursery of Krymka obtained from intravarietal crossing, where on different F2 plots (separate families) there is a varying degree of uniformity, the offspring of the different hybrid plants of the same combination do not vary in the same degree. There are hybrid plants which may not show sharp diversity in any generation, beginning with the first, i.e., will not show what is usually called segregation. On the other hand, there may be hybrid plants of the same combination, the progeny of which show great diversity of forms, i.e., segregate. The importance, however, of finding in the first hybrid generation constant plants that produce relatively uniform progeny resembling the first hybrid generation is very evident to us seed growers and plant breeders. The first hybrid generation of wheat, cotton and other plants fairly often turns out to be so good that if the given variety could be kept in this state in future, plant breeders would, in many cases, be more than pleased with their work. It appears that this can be done. This is definitely shown by the Krymka winter-wheat nurseries which are planted with seeds from an intravarietal crossing. Until now, I (and I think all other specialists) did not know this. I was prevented from knowing this by genetics, which told us, and now still tells us, that in all cases hybrids must segregate in F2, and that there can be no constant hybrids.
No small role in the creation of uniformity of hybrid progeny obtained from the crossing of morphologically sharply different forms within the Krymka variety is played by the capacity for elective fertilization. The castrated wheat plants of the Krymka population were allowed much greater freedom to choose pollen grains than is the case in artificial crossing. We know that the more difficult the crossing of two given forms of plants, the more diverse is the progeny of such a cross. It is not for nothing that the term "crazy" segregation has been introduced in genetics to indicate the progeny of plants difficult to cross. When the crossing Is easy, for example, one variety of wheat with another, the progeny is less diverse.
It is not difficult to arrive at the conclusion that the more one gamete (sex cell) biologically corresponds to the other during fertilization, the more stable and less diverse will the progeny of this cross become in the succeeding generations.
Geneticists, the advocates of inbreeding (the enforced self-pollination of cross-pollinators), know very well, although they say nothing about it, that the seeds of individual rye plants, or of beetroots obtained by free pollination in the field with the pollen of other plants produce a much more uniform progeny than seeds from the same plants subjected to enforced self-pollination. The whole point, in my opinion, is that the first case provides greater possibilities for the uniting of sex cells that are more fit for each other. That is why a progeny resulting from intravarietal cross-pollination is not only more viable, but also more uniform than offspring resulting from enforced self-pollination.
It is possible, and sometimes necessary, to "violate" the nature of plants, but in doing so it is absolutely necessary to reckon with biological laws.
The more arbitrarily the nature of plants is violated, the less consideration is paid to biological development, the less useful such plants become. Only by agrotechnique, by kindly and skilful treatment of the nature of plants, by showing consideration for their requirements, do people obtain ever-increasing yields from plants. All the more necessary is it, therefore, to treat the nature of plants gently and skilfully if one wants to grow good seeds.
The nursery containing the, second generation obtained from the intravarietal crossing of Krymka by means of free wind pollination shows us that it is possible to hybridize in such a way as to obtain comparatively uniform hybrid progeny. In nature there is no such thing as Mendelian segregations invariably in the ratio of (3:l)n. Mendel's so-called law is not a law of biological phenomena, but of averaged, impersonal statistics. As is well known, Mendel himself attached no importance to the deductions from his experiments. This is shown even by the fact that as soon as his leisure was curtailed, when he was promoted from monk to abbot, he gave up his hobby of experimenting with plants. Mendel has nothing whatever to do with biological science. The postulates of Mendelism, developed not by Mendel, but by the Mendelist-Morganists, give us no effective guidance in our practical work of seed growing. As my own experience has convinced me, they are quite a hindrance to the improvement of seeds.
If I have sharply attacked the stronghold and foundations of the science of genetics, if I have made a trenchant assault on Mendel's law, which has been and is now being touched up by the Morganists, it is primarily because this law greatly hinders me in my work, or, to be more specific, hinders the work of improving the seeds of cereals.
First published in 1938