Agrobiology p 260-261 (1954)
T D Lysenko

1Cf. I. V. Michurin, Selected Works, Eng. ed., Moscow 1950, p. 25.
However, on the question of how to induce noncrossing species and genera to cross, a wealth of material can be found in the works of I. V. Michurin based on his brilliant practical achievements. For example, in his article "My Experiments in Breeding New Plum Varieties in a Severe Climate" Ivan Viadimirovich wrote that, as far back as the spring of 1889, he hastened to take advantage of the second flowering of his blackthorn, expecting, not without reason, that a young plant, which had not yet had time to develop resistance to fertilization with pollen of a distantly‑related variety, would be easier to fertilize as he desired with pollen of Green Reine Claude.1

In the same article I. V. Michurin emphasizes that all his attempts to cross blackthorn with the Green Reine Claude plum failed owing to the too distant kinship between these two plants. Only after he had taken a young blackthorn plant did he obtain twelve fruits out of fifteen pollinated flowers. At all events, he achieved a larger percentage of success than is obtained by any treatment with the poison colchicine, or acenaphthene, which are now so much in vogue among our Mendelists.

From these seeds of hybrids of distant forms, which usually fail to cross and, as we know, have different chromosome numbers, Michurin obtained plants that not only were not sterile but could be termed excellent varieties. The Mendelist geneticists, who mutilate plants with poisons and resort to other forms of violent treatment, assert that they are working out a method of making sterile distant hybrids fertile. No, the art of crossing distant species and of obtaining fertile progeny from such crossings must be learnt from the works of I. V. Michurin.

I. V. Michurin was not only able to obtain good varieties himself, but he elaborated a splendid theory which serves as the basis on which numerous Soviet Michurinists are doing brilliant work along the line of creating new forms of the most diverse plants by means of intergeneric and interspecific crossing. I will mention a few such examples.

From the crossing of the wild potato species Akaule [Solanum acaule Bitter] with cultivated varieties hybrids rarely result, and when they do they are of wild appearance and produce hardly any tubers. Such hybrids have to be pollinated repeatedly for several generations with the pollen of cultivated varieties, i.e., they have to be impregnated all the time with a cultivated variety. Only after that is done can a variety with cultivated characters be obtained. Of course, some of the wild plant's good properties, for the sake of which it was taken for crossing, are in many cases entirely lost in the process.

A. S. Filippov, a young Soviet scientist at the Potato Institute, tackled the problem of crossing distantly‑related forms of potatoes in the Michurin manner. He grafted a plant of the wild potato species on to a cultivated variety (the Michurin method of approximation). When flowers appeared on the wild scion he pollinated them with the pollen of the cultivated variety. In the very first generation (i.e., after a single crossing between the wild and the cultivated species) a cultivated type appeared, at all events, one much more cultivated than the plants growing next to it of the same wild species, which for three consecutive generations had been pollinated with the pollen of cultivated varieties.

Another example. Solodovnikov, a postgraduate at the Potato Institute, obtained vegetative hybrids from a cross between a cultivated potato and a wild potato. These hybrids, grown from the stolons of the wild species Demissum [Solanum demissum Lindl.] (the stock), already have the appearance of cultivated potatoes.