8 TABOO AND GENETICS 



development and all the higher, more compli- 

 cated animals are sexual. This crossing of 

 strains may make possible greater variety, it 

 may help in crossing out or weakening variations 

 which are too far from the average, or both. 



Schafer (4) thinks that an exchange of nuclear 

 substance probably gives a sort of chemical 

 rejuvenation and very likely stimulates division. 

 At any rate, the groups in which the reproductive 

 process became thus partitioned between two 

 kinds of individuals, male and female, not only 

 survived, but they underwent an amazing 

 development compared with those which re- 

 mained sexless. 



There came a time in the evolution of the 

 groups possessing sexual reproduction, when 

 increasing specialization necessitated the division 

 into reproductive and non-reproductive cells. 

 When a simple cell reproduces by dividing into 

 two similar parts, each developing into a new 

 individual like the parent, this parent no longer 

 exists as a cell, but the material which composed 

 it still exists in the new ones. The old cell did 

 not " die " — no body was left behind. Since 

 this nuclear substance exists in the new cells, 

 and since these generations go on indefinitely, 

 the cells are in a sense " immortal " or deathless. 

 In a one-celled individual, there is no distinction 

 between germinal and bodily functions. In the 

 more complicated organisms, however, there are 



