Studies on Chromosomes. 



385 



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

 Figs. 5/7, /, /, 4, Jn l 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 



1\ 



h 



FIG. 5. 



Coenus (a-j, '), Lygaeus (g, h*), Euschistus (y), Podisus (A), a, Coenus, contraction-phase, showing 

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

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

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

 g, h, spermatogonial metaphase-groups, Lygaeus; /, spermatogonial group, Coenus; j, spermatogonial 

 group, Euschistus, sp.; k, spermatogonial group, Podisus. 



somes may be symmetrically paired ofF, two by two, while 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. 



