SEX CONDITIONS 



has been made in both the normal and biparental 

 males. Following the spermatogonial divisions, 

 both kinds of males show an abortive first mat- 

 uration division--a small bit of the cytoplasm 

 being pinched off at the narrow end of a pear- 

 shaped cell. This division of the sperm cell in 

 the male is comparable to the reduction or mei- 

 otic division of the egg, at which time the 

 paired chromosomes separate, forming abortive 

 polar bodies and one haploid egg nucleus. Eggs 

 if unfertilized by sperm will hatch into normal 

 haploid males. If fertilized, they will pro- 

 duce normal diploid females; and in abnormal 

 cases, diploid biparental males. 



It has been shown (Speicher, 1935; Risman, 

 1941) that diploid males have much larger cells 

 than diploid females, while haploid males have 

 cells approaching the diploid female size. It 

 seems possible that large cell size might be 

 responsible for the high diploid male mortality 

 and that a demonstrable difference in cell size 

 might appear between diploid males differing in 

 mortality. 



In developing Habrobracon it is observed that 

 each bristle on a wing surface corresponds to 

 and gives indication of the presence of a wing 

 surface cell (Speicher, 1935). Since each cell 

 of the single layer forming the upper surface of 

 the wing bears a single bristle (microchaeta) , 

 variations in cell size produce proportional 

 variation in dispersal of bristles. Thus, if 

 fewer michochaetae are noted per unit area 

 larger cells are present in the wing surface. 

 A tendency toward larger cell size in diploid 

 male material with higher mortality is indi- 

 cated in microchaetal evidence. The tendency is 



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