350 PLANT HYBRIDIZATION BEFORE MENDEL 



cially form) of the crossed product, when it furnished the ovary, than 

 when it furnished the pollen." (p. 236.) 



The obtaining of a 3: l ratio in the F^ from his own results is 

 stated by von Tschermak as follows : 



"In the seeds of the hybrids (in the first generation), obtained through 

 self-fertilization, the characters yellow and smooth showed themselves, 

 exactly as in the cross-pollinated seeds of the mother plant, as of higher 

 value or hereditary potency than the characters green and wrinkled. 

 While, however, in the artificial breeding of products of heteromorphic 

 xenogamy, the first named characters are almost without exception domi- 

 nating, while the latter, 'recessive,' only in individual cases come to light 

 pure or as admixture, the former characters in the seeds of the first 

 hybrid generation only in the majority of cases get into expression pure ; 

 in the minority, the recessive characters come out pure. In the first 

 case there thus exists an almost absolute dominance, in the second 

 mere superiority ['Pravalenz'] (in a certain relationship). Mixtures of 

 both character groups are here also seldom, but perhaps less seldom than 

 there. The number of the bearers of the dominating or. prevailing char- 

 acter, to that of the bearers of the recessive, is related about as 3:1. The 

 comparison of the derivatives from reciprocal crossing of different va- 

 rieties showed, analogously to the results given above for the products 

 of reciprocal pollination, that in certain experimental cases the egg cell 

 appears to be a more operative bearer of the dominating color-character, 

 than the pollen cell. But for the proposition of a statement in this regard 

 further investigations are needed. The combination of two dominating or 

 recessive characters in one parental form carries with it the same behavior 

 in the seed production of the hybrids, as the characters in question do 

 when isolated. An alteration in the value, such as an increase of the 

 dominance [Pravalenz], does not thereby enter in." {ib., p. 236.) 



This closes the essentially Mendelian portion of the above 

 paper, "tJber kiinstliche Kreuzung bei Pisum sativum.'' The 

 Zeitschrift fiir das landwirtschaftliche Versuchswesen in Oester- 

 reich, III Jahrgang, 1900, pp. 465-555. (3b contains the complete 

 report, of which the article in the Ber. d. d. hot. Ges. 18:232-9 

 was a preliminary account.) The complete account follows: 



The experiments in question were begun in the Botanical Gar- 

 den at Ghent in Belgium in the spring of 1898. Yon Tschermak 

 says (letter to the author of January 7, 1925) : 



"The principal incentive to the experimental work lay in the results 

 of Darwin's experiments on 'The Effects of Cross and Self Fertilization 

 in the Vegetable Kingdom,' (1877). The experiments prove that seedlings 

 from a cross between individuals of the same species almost always 

 exceed in height, weight, vigor of growth and frequently also in fertility, 

 the corresponding individuals produced by self-fertilization." (3b, p. 465.) 



"The result," says von Tschermak, "formed the first instigation to my 

 researches, which, on the one hand, on account of the significance of this 

 question for the science of plant breeding, on the other hand, on account 



