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If we compare these results with the effects of selection in twisted and fasciated races, we observe a marked contrast. Here they reached their height at 30-40%, and no number of generations had the power of making any further improvement. The tricotyls come up in two generations to a proportion of about 54%, which shows itself to correspond to the average type.
The accordance of these facts with the experience of breeders of domestic animals, and of Louis de Vilmorin, and with the result of the theoretical considerations concerning the factors of fluctuation has led me to suggest the method of selecting, which I have made use of in my experiments with tricotyls and syncotyls.
Often a character is only developed once in the whole course of evolution, as for instance, the degree of connation of the seed-leaves in tricotyls and in numerous cases it is impossible to tell whether a character is individual or partial. Consequently such minute details are generally considered to have no real importance for the hereditary transmission of the character under discussion.
The stray tricotyls themselves, that are sought out from among the original samples, give hereditary percentages of a much higher type after isolation than those quoted above.
Starting points are the stray tricotyls which are occasionally found in ordinary sowings. In order to increase the chance of finding them, thousands of seeds of the same species must be inspected, and the range of species must be widened as much as possible. Material for beginning such experiments is easily obtained, and almost any large sample of seeds will be found suitable.
Besides these tests, others were performed, based only on the visible characters of the seedlings. The result was that this characteristic was almost useless as a criterion. The atavists gave, in the main, nearly the same hereditary percentages as the tricotyls and syncotyls, and their extremes were in each case far better constituted than the average of the chosen type.
They come up to 10-20% and in some cases even to 40%. As may be expected, individual differences occur, and it must even be supposed that some of the original tricotyls may not be pure, but hybrids between tricotylous and dicotylous parents.
These are at once eliminated by selection, and if only the tricotyls which have the highest percentages are chosen for the continuance of the new race, the second generation comes up with equal numbers of dicotyls and tricotyls among the seedlings. The figures have been observed to range from 51-58% in the majority of the cases, and average 55%, rarely diverging somewhat more from this average.
In some instances the degree of their inheritance is only a very small one. The isolated tricotyls yield 1 or 2% of inheritors, in some cases even less, or upwards up to 3 or 4%. If the experiment is repeated, no amelioration is observed, and this result remains the same during a series of successive generations. Such poor races hardly afford a desirable material for further inquiries.
The first feature is the hereditary percentage. But then not all the seedlings of the selected parents can be planted out, and a choice has to be made. This second selection may favor the finest tricotyls, or the strongest individuals, or rely on some other character, but is unavoidable. We now come to the description of the cultures.
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