No. 613] 



53 



other parts of the plant, since, as was already noted, yel- 

 low cotyledons are accompanied by green seed-coats in 

 certain varieties. 



The crossing experiments which have been made by the 

 author since 1910 with these different types of beans have 

 produced the results shown in Table I, the main facts 

 being summarized as follows. 



I. The Fj cotyledons of the crosses reciprocal to each 

 other are of the same character as the female parents. 

 In respect to the cotyledon colors, the F 2 and following 

 generations show the characters of the Fj generation ex- 

 clusively, instead of a Mendelian segregation between the 

 yellow and green colors. Hence we are probably dealing 

 with characters which can be inherited only through the 

 female parents. 



H. The inheritance of the seed-coat colors is a more 

 complicated phenomenon. In the cross "green cotyle- 

 dons, green seed-coat" (?) X "yellow cotyledons, yellow 

 seed-coat" the green seed-coat is inherited through 

 the female parent exclusively, just as in the case of the 

 cotyledon colors; but in the reciprocal cross the green 

 and yellow seed-coats show Mendelian segregation, the 

 former being dominant. 



The maternal inheritance observed above was not due 

 to self-fertilization succeeding failures in artificial cross- 

 ing, because several other characters showed inheritance 

 through the male parents. 



An interpretation of the inheritance phenomena under 

 consideration is suggested as follows. In the first place, 

 let us refer again to the two different kinds of chlorophyll 

 assumed to be concerned in producing the green and yel- 

 low cotyledons ; namely, the chlorophyll which can be 

 changed into yellow and the chlorophyll which remains 

 green. (These will be denoted respectively as "(Y)" 

 and "(G)" in the later descriptions.) These character- 

 istics of chlorophyll may be due to heritable traits of the 

 chromatophores or of the cytoplasm, and not to hered- 

 itary element.- in the nucleus. As, on the fertilization of 



