CYTOPLASMIC INHERITANCE 221 



contains both kinds, more white granules than green ones 

 may at times get into a cell, and at other times only white 

 granules will get into one daughter cell, so that a wliite 

 branch arises. 



In other species of plants that have white leaves and 

 branches and green leaves and branches, the cross may 

 give a different result. Thus in Melandrium and Antirrhi- 

 num, green by white gives green F, (whicliever way the 

 cross is made), in F. there are 3 green to 1 white plant. 

 In this case the results can be explained as due to the 

 action of genes in the chromosome on the production of 

 chlorophyll in the cytoplasm— an action of such a kind that 



Fig. 103. — Pelargouium that gave rise to a white branch. (After Baur.) 



the granules do not develop green color unless the (nor- 

 mal) gene is present, in single dose at least. In this case, 

 even if the eggs only transmit plastids, the F^ individual 

 from a white-leaved mother by a green-leaved father is 

 green, because the paternal nucleus introduces a gene 

 that causes the green color to develop in the plastids. It 

 is the segregation of the genes in the germ-cells of the F^ 

 individual that leads to the 3 : 1 ratio in F., and not the 

 distribution of the plastids as in the preceding case. 



The most peculiar case is that of Pelargonium de- 

 scribed by Baur. White leaves and branches, and green 

 leaves and branches occur on the same plant (Fig. 103). 

 Self-fertilized seeds from each breed true to color of 

 branch. White to green gives a different result, viz., 



