SEX 85 



"white" x. Such are males and are necessarily white- 

 eyed. In the next generation the sperms from the 

 male carry no red, but of the egg cells from the heterozy- 

 gous female half carry red, the other half not. Each 

 half is equally likely to be fertilized by a male- or 

 female-producing sperm ; hence there are both red- and 

 white-eyed males and females. Similar facts were de- 

 veloped in numerous other cases, proving that the sex 

 chromosome carries other determiners than that for 

 sex, and at the same time confirming the sex chromo- 

 some theory. 



7. Although sex is said to be determined by the germ Gynandro- 

 plasm of the zygote, and therefore decided at the mo- 



ment of fertilization, there are various apparent excep- acters of 



... . . j j i both sexes 



tions and complications. Among insects individuals 



occasionally appear which combine the characters of 

 the two sexes in a remarkable way ; these are called 

 gynandromorphs. A certain kind of parasitic wasp not 

 only has the sexes differently colored, but whereas the 

 males are winged, the females are wingless. A speci- 

 men was found in which the right side showed the male 

 characters, with wings, and the left those of the female, 



Drawing by R. Weber 



FIG. 19. Face of gynandromorphic bee (Melissodes), the clypeus showing the color 

 of the male (light) on one side, of the female (dark) on the other. 



