CH. xi] GALL-FLIES 153 



in the social species, such as bees and wasps, subsequent 

 treatment of the female larva may turn it into a worker or 

 a queen, but never into a male, nor a' male larva into a 

 worker. In the Gall-flies (Cynipidae) the difference between 

 the eggs with the haploid and diploid chromosome numbers 

 is produced in a different way, for both males and "sexual" 



" 





 



y \ s=^ > t - 



* e 'A 



./: >:* . ...; 



''::: ,* ' * 



FIG. 17. Chromosome-groups of dividing cells in the Gall-fly 

 Neuroterus lenticularis. (Preparations by the writer.) 



a. Diploid equatorial plate in ovary of sexual female. 



b. Diploid anaphase group in ovary of sexual female. 



c. Diploid anaphase group in nervous system of female larva (cf. e}. 



d. Diploid equatorial plate of segmentation divisions in egg of spring 

 (agamic) generation, which would develop into a female (cf. g). 



e. Haploid metaphase group in nervous system of male larva ; each 

 chromosome split (cf. c). 



f. Haploid anaphase group in spermatogonial division. 



g. Haploid anaphase group in segmentation division in egg of spring 

 (agamic) generation, which would develop into a male (cf. d). 



females arise from parthenogenetic eggs. These eggs are of 

 two kinds, laid by two classes of females ; those of one kind 

 undergo a double maturation division, leaving the haploid 

 number of chromosomes in the egg, and grow up into males, 

 while those of the other kind have no maturation division 

 and have thus the diploid number and develop into fe- 

 males. 



