TABOO AND GENETICS 7 



different condition is found in those orders where 

 the numerous cells thus produced by simple 

 division of the parent organism unite in pairs 

 to produce new individuals after a brief in- 

 dependent existence of their own. These 

 free-swimming cells, which apparently are formed 

 only to reunite with each other, are called zoo- 

 spores, while the organism which results from 

 their fusion is known as a zygospore. The 

 zj^gospore thus formed slowly increases in size, 

 until it in its turn develops a new generation 

 of zoospores. In still other forms, in place of 

 the zoospores, more highly differentiated cells, 

 known as eggs and sperms, are developed, 

 and these unite to produce the new individuals. 

 Both eggs and sperms are believed to have been 

 derived from simpler ancestral types of ciliated 

 cells which were similar in structure and closely 

 resembled zoospores.* 



Having once originated, the sexual type of 

 reproduction possessed a definite survival value 

 which assured its continuation. Sex makes 

 possible a crossing of strains, which evidently 

 possesses some great advantage, since the few 

 simple forms which have no such division of 

 reproductive functions have undergone no great 



*This evidence, which points to the conclusion that in the 

 early origin of sexual reproduction the males and females 

 were differentiated and developed from a uniform type of 

 ancestral cell, quite controverts Ward's point that the male 

 originated as a kind of parasite. 



