232 FRANK A. HARTMAN. 



PLATE I. 



FIGS. : to 24 inclusive. Polar view of chromosomes in first spermatocyte meta- 

 phase. Drawings of this and the succeeding plates made with the aid of a camera 

 lucida. 



Figs, marked A are from adults, A and A 1 being from different animals. Figs, 

 marked n are from young nymphs, n, n 1 , w 2 , 3 , w 4 being from different animals. 

 Chromosomes are numbered according to their size in the cell beginning with the 

 smallest. The difference in size between nymph and adult cell chromosomes is 

 very striking. A comparison of corresponding chromosomes of different cells 

 of the same animal shows the variation in size mentioned in this paper. 



