354 PLANT HYBRIDIZATION BEFORE MENDEL 



In the whole of the paper, the author by preference uses the 

 word "Mischling" for crosses made between varieties of the same 

 species. 



"since the forms of peas used by me, according to the general view at 

 present, represent varieties of one and the same species, Pisum sativum 

 L., I designate the products of their crossing (heteromorphic xenogamy) 

 as 'Mischlinge,' not as hybrids ['Bastarde']." {ib., p. 521.) 



This paragraph clearly shows the transition state of mind be- 

 tween the earlier point of view regarding "hybrids," in which 

 the product was regarded as a whole, and from the a priori stand- 

 point of the degree of closeness of relationship of the two par- 

 ents, and demonstrates that the idea of the crossing of competi- 

 tive characters, i.e., of what has been later denominated the con- 

 tending of two members of an "allelomorphic" pair, as being a 

 universal phenomenon no matter what the degree of relationship 

 of the parents, had not yet gained a certain foothold. In von 

 Tschermak's paper of 1900, we still see that the crossed plant 

 product was being thought of as a whole, rather than in terms of 

 its individual character-factors regarded singly. 



Considerable experimental work follows in the von Tschermak 

 paper on the relative height, etc., of self-fertilized individuals, 

 individuals from crosses upon the same plant, and on different 

 plants of the same variety, in the case of peas. The following 

 conclusion was arrived at: 



"From the whole of my experiments it results that, in the sorts of 

 Pisum sativum used, a cross between different flowers of the same indi- 

 vidual, as between flowers of different individuals of the same variety, 

 brings no advantage to the descendants, in comparison to the plants pro- 

 ceeding from self-fertilization." {ib., p. 522.) 



In this conclusion the writer confirms wholly Darwin's experi- 

 ments. 



A further conclusion from the series of experiments is arrived 

 at in general, that : 



"Among the twelve hybrid forms [Mischlingsformen] cited, there ac- 

 cordingly results in probability a simple taking-over of the paternal 

 height-character, but no proof of a height excess through crossing in 

 itself, in contrast to self-fertilization. The hybrids in question stand in 

 height either between the parents, and indeed nearer the higher mem- 

 ber, or resemble them." {ib., p. 530.) 



From further cases of exceptions, he concludes : 



