328 



MR. L. T. HOGBEN ON CERTAIN NUCLEAR PHENOMENA 



were collected by Prof. Doncaster, but as it was difficult at the time to 

 procure many, the closely-allied species N. numismatis was also studied, 

 late pupte and egg-masses of newly-hatched flies being preserved in addition 

 to the November material. For the latter Flemming was used, egg-masses 

 being preserved in Bouin or Gilson's fluid. Sections were cnt 4-6 m. in 

 thickness and stained with Heidenhain's iron hematoxylin and eosin. The 

 preparations were examined with a Zeiss - 2 immersion and apochrom. ocular 

 No. 12. 



The Somatic Mitoses. 



Fifty counts were made of the dividing nuclei of the developing wing, 

 nervous system, and follicular epithelium of Nev.roterus numismatis. The 

 average was 19 - 2, 26 giving 20 and the rest 18 or 19. Some of the figures 



Fig. 1. 





':f\Vrs^~ 



'}'s 





(} 



m' 



fit 



V-S: 



M 



1-6. Pairing of the chromosomes and formation of the abortive maturation spindle 

 in Neuroterus numismatis. 



giving 20 were very clear, and there is no doubt that the diploid number for 

 this species is the same as for N. lenticularis, viz. 20. 



Very clear figures of abnormal mitoses were found in the hypoderm cells 

 of larva? of N. lenticularis. Doncaster has figured in his second paper the 

 anaphase of one of the giant cells which lie below the epidermis showing 

 at least 50 chromosomes at each pole. In several cases of cells of the 



