THE CHROMOSOMES OF THE CERCOPID/E. 139 



cyte division. The odd chromosome in the early growth stages 

 of the spermatocytes varies in shape in the different species. 



2. The individuality of certain chromosomes was traced in 

 these two species of Cercopidse. In both, the reduced number 

 of chromosomes is 12. In Philcenus, the identity of one large 

 and two medium-sized chromosomes can be traced in the primary 

 spermatocyte, secondary spermatocyte, spermatogonium, oogo- 

 nium and male and female somatic cells. The odd chromo- 

 some is always one of the smallest. In Aphrophora, one largest 

 chromosome always appears. 



3. The somatic variation in both species is very marked, but 

 there is no corresponding variation in the composition of the 

 chromosome groups. 



UNIVERSITY OF MAINE, ORONO, 

 November, 1912. 



