HEREDITY AND SEX 



N or simplex number. The eggs of most ani- 

 mals, after they have undergone reduction, are 

 incapable of development unless fertilized, but 

 those of the hymenoptera may develop either 

 fertilized or unfertilized. In the former case 

 a female is produced, in the latter a male. The 

 simplex, or N condition is in this case the male, 

 the duplex or 2 N condition is the female, natu- 

 rally the one of higher metabolic activity, the 

 one which forms the macro-gametes. 



In an earlier chapter I explained how the 

 development of the sperm-cells in a male having 

 the reduced or simplex number of chromosomes 

 differs from that in the ordinary male. Eefer- 

 ence to Fig. 8 may help to recall this. The 

 cells of the male are in this case already in the 

 reduced or simplex condition, N. In the pro- 

 duction of the sperms the reducing division is 

 omitted so far as nuclear components are con- 

 cerned, so that each sperm formed contains the 

 full simplex chromosome number, N. If it were 

 less, the gamete formed would perhaps not be 

 capable of transmitting all the hereditary char- 

 acteristics of an individual. 



A second category of cases (Fig. 49, middle 

 163 



