54 



THE AMERICAN NATURALIST [Vol. LII 



the egg-cell, the chromatophores and the cytoplasm of the 

 female gamete will probably remain as such without 

 being supplemented by those from the male gamete, their 

 characteristics would naturally be inherited only through 

 the female parent. In the second place we may assume 

 that a pair of Mendelian factors is concerned in the inher- 

 itance of the colors of the seed-coats. The factor "H" 

 inhibits the chlorophyll "(Y)" in the seed-coat of the 

 beans with yellow cotyledons from changing to yellow, 

 producing beans with yellow cotyledons and green seed- 

 coat; the absence of the factor "H," expressed by "h," 

 allows the seed-coat of the bean with yellow cotyledons to 

 remain yellow. The seed-coat of the bean with green 

 cotyledons remains green no matter whether the factor 

 "H" is present or absent, because the beans of this kind 

 have the chlorophyll " (G) " which is incapable of chang- 

 ing the color. 



The justice of the contention regarding the bean with 

 green cotyledons, moreover, is supported by the following 

 observations. The F 2 families of the crosses "green 

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

 yellow seed-coat" (J 1 ) were actually composed of two 

 kinds of individuals which were distinguishable from each 

 other by a slight difference of the intensity of green color 

 in the seed-coats, and the numerical relation between these 

 two kinds of individuals was approximately the Mendelian 

 mono-hybridal segregation ratio, the darker seed^coat 

 being dominant to the lighter one. Again, in the F 3 gen- 

 eration of these crosses, there were obtained three types 

 of families, two which were uniformly of the darker and 

 of the lighter seed-coats respectively and one which was 

 a mixture of both. By comparing the green seed-coats of 

 the female parents in these crosses with those of the prog- 

 eny, the former was found to belong to the darker class 

 mentioned above. These variations in the green color of 

 the seed-coats may be regarded as being due to the in- 

 fluence of the Mendelian factors "H" and "h" respec- 

 tively on the chlorophyll "(G)"; from which it follows 



