The Situation in Biological Science, pp. 178-179 (1948)
Vegetative Segregation
A. A. Avakian

The numerous spring varieties that have been obtained by directed training from winter varieties develop as spring varieties when sown in the spring; similarly, hybrids obtained by crossing winter varieties, converted into spring varieties with the initial winter varieties, develop as spring varieties. By training we have also obtained winter varieties from hereditary spring varieties. Changed organisms, not having yet acquired a stable nature, are very susceptible to the moulding conditions of life.

In this connection, the hardy winter varieties obtained in Siberia from spring varieties by means of autumn sowing are of great interest.

The rule of the dominance, the purity of the gametes, is regarded as one of the fundamental laws of Morganism. Morganism utterly repudiates the possibility, of directing dominance in the first hybrid generation. From the standpoint of the Michurin theory, it is possible and necessary to direct the development of hybrid plants.

It is known that in crossing winter with spring varieties the first generation develops as a spring variety. Is it possible to conduct the work in such a way that the first generation should develop as a winter, and not as a spring variety? It is. To achieve this, spring varieties, the spring variety of rye in particular, are sown before crossing in the autumn.

Spring rye plants, sown in the autumn, are repollinated in the following year with the pollen of winter varieties of rye. When we sow such hybrid grains, the progeny of every ear produces a large number of winter hybrid plants, in which winter type of development is dominant. It is very important that in the majority of cases the offspring of these hybrid plants develop according to the winter type. Only individual plants produce a small number of spring plants.

From the standpoint of Mendelism-Morganism, the nature of the divergencies in the second generation of hybrid organisms is conditioned by the chance separation of the chromosomes during the reduction division.

According to the Michurin theory, this divergence is conditioned by relatively different somatic cells from which the sex cells are formed. Hence, from the standpoint of Mendelism-Morganism, it is impossible to direct divergence in hybrid progeny; from the Michurin standpoint, however, it is possible to regulate and direct the nature of the divergencies in the second and subsequent generations.

It is known that many varieties of bulbous plants, in addition to forming seeds, can produce aerial bulbs. We deliberately took hybrid plants, which, after flowering, produced both seeds and aerial bulbs. All that has to be done for this is to remove the buds before flowering. When we sow the seeds and the aerial bulbs we obtain variations in the colour of the bulb, in the form of the bulb, both in the progeny arising from the seeds and from the aerial bulbs.

These examples show that diversity in hybrid progeny is not due to the chance separation of the chromosomes during reduction division, but to the fact that in the process of the individual development of the organism the somatic cells from which the sex cells are formed change their nature.

Simultaneously with this work, we studied another problem, which in our opinion is of great theoretical interest.

It is the accepted thing in Mendelist-Morganist literature to regard the process of rejuvenation as being connected with the reduction division. We, however, assume that the process of rejuvenation should be a property of both the sex cells and the natural vegetative reproductive organs. We assume that the somatic cells from which the sex cells are formed become young. For this purpose we used bulbous plants.

It is known that winter varieties of garlic, in addition to bulbs which form at the bottom, form bulbs also on the flower-bearing shoot. If the aerial bulbs formed from cells which have passed through all stages of development are planted, the organisms obtained from these bulbs do not flower in the first year, nor in the next year if they are reared in warm temperatures. From many strains of onions we obtained aerial bulbs and seeds. It has been proved experimentally that plants obtained from seeds and from aerial bulbs require the same conditions for passing through the stages of development anew. This shows that the property of beginning individual development anew is not conditioned by the reduction division, but by definite somatic-maternal cells from which the sex cells are formed.

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