116 HEREDITY AND ENVIRONMENT 



PCh 



Fig. 26. StrccEssni; Stages in the Cleavage of the Egg 

 or A MoLLtJSK (Orepidula), showing the separateness of the 

 male and female chromosomes (^ ch, J ch) and of the male 

 and female halves of each nucleus (,(SN, JiV). 



