18 THE CELL AND HEREDITY. 



Amphimixis, mingling of chromatin units ; idants, 

 ids, biophores, gemmules. This mixing supposed to 

 correspond to the mixing of elements of character or 

 of structure in the new individual. Dimorphism of 

 living beings. Primary purpose of amphimixis to in- 

 crease variation. Lack of variation means destructive 

 competition and wasted opportunities. 



Parthenogenesis ; its occurrence when an immediate 

 brood is needed, and variation undesirable. A char- 

 acter of degeneration. Its analogy to budding. 



The polar bodies. Their origin and significance. 

 Female mother cells form four daughter cells. These 

 unequal ; one with food yolk and half normal amount 

 of chromatin. The three others (polar bodies), with- 

 out food yolk, are cast off and do not develop. Male 

 mother cells divide into four daughter cells, all alike. 

 Studies of Ascaris. 



