^ 



Studies on Chromosomes. 



38; 



that the larger chromosomes may be grouped in six pairs; and in 

 Figs, ^hy i, j, 4.g, Jn^ I have attempted to indicate these by corre- 

 sponding numbers; though no pretense to complete accuracy of 

 identification can be made, since the chromosomes vary somewhat 

 in form and their apparent sizes vary somewhat with their posi- 

 tion, owing to foreshortening. Allowing for all errors of identifica- 

 tion it is obvious that in all but Nezara 12 of the larger chromo- 







g 



h 





Fig. 5. 

 CcEnus (fl-/, /), Lygaeus {g, /;), Euschistus {j\ Podisus (i). a, Cosnus, contraction-phase, showing 

 both idiochromosomes in the form of chromosome-nucleoli; h, prophase, corresponding to stage h in 

 Lygaeus, the two idiochromosomes and four of the others; c-/, chromosome-nucleoli of Ccenus from a 

 stage corresponding to stage /; r, d, both idiochromosomes present, c, f, single chromosome-nucleoli; 

 g, h, spermatogonia! metaphase-groups, Lygseus; /, spermatogonia! group, Ccenus; j, spermatogonia! 

 group, Euschistus, sp.; k, spermatogonia! group, Podisus. 



somes may be symmetrically paired off, two by two, w^hile a 

 thirteenth (unnumbered in the figures) is left without a fellow of 

 like size. The conclusion is, I think, irresistible that in synapsis 



^In the last figure the chromosomes have been by inadvertence wrongly lettered. 



