340 PLANT HYBRIDIZATION BEFORE MENDEL 



"The characters through which the races of peas are distinguished, 

 one can, as generally, arrange together in pairs, in which every member 

 of a pair relates to the same point, the one with the one, the other with 

 the other race, e.g., to the color of the cotyledons, of the flower, of the 

 seed-coat, of the hilum on the seeds, etc. In many pairs, the one char- 

 acter, or as the case may be the primordium [Anlage] of it, is so much 

 'stronger' than the other, or e.g., the primordium, that only it alone 

 comes to light in the hybrid plant, while the other throughout does not 

 show. One can call the one the dominating and the other the recessive, 

 as Mendel did in his time and, through a remarkable accident, De Vries 

 does also now. Dominating, is, for example, the yellow color of the 

 cotyledons as opposed to green, the red of the flower as opposed to 

 white.'' (p. 159.) 



"It is, however, quite incomprehensible to me, as De Vries is able to 

 assume, that in all character-pairs in which the two races differ there 

 is one dominating pair-member in the hybrid." [The author here quotes 

 from De Vries, as follows: Comptes Rendus, 1900, p. 845: "Per contra, 

 the study of the simple characters of hybrids is able to furnish the 

 most direct proof of the principle enunciated — the hybrid shows always 

 the character of one of the two parents, and that always in all its force; 

 never is the character of the parent, which is lacking to the other one, 

 found reduced by half."] 



"Even in the races of peas, in which several character-pairs correspond 

 exactly to the scheme, there are others in which no character dominates ; 

 thus the color of the seed-coat, whether red-orange, or greenish-hyaline. 

 Then again, the hybrid can show all transitions, even in the seed-coat 

 of peas, or it shows always more of one than of another character, as 

 Stocks hybrids, in which, for example, a given hybrid can still be dis- 

 tinguished from the one parental race by the markedly weaker pubes- 

 cence, but always, after some examination ; while with the other, the 

 smooth parental race, it extraordinarily contrasts." (p. 160.) 



For some two pages and a half, Correns then outlines Men- 

 del's general results with a single pair of allelomorphs, and fol- 

 lows with a tabular statement of his individual results. 



Experiment I 



Cross between late Erfurt green "Folgeerbse" with green cotyle- 

 dons, and "purple-violet" (Schlesien) "Kneifelerbse," with yellow 

 cotyledons. 



Generations 



Fi 51 yellow (19 planted) 



Fo 619 yellow (25 planted) 260 green (25%) (11 planted) 



7 yellow (28%) 



F: 



3 



251 yellow 550 yellow 195 green (26.2%) 538 green 



(7 planted) (18 planted) (14 planted) (10 planted) 



