CHROMOSOME COMPLEX OF SPERM ATOCVTES. 



313 



which slides were made, and so I am not sure whether I have 

 H. pratensis or H. viridis. I am tolerably sure that both are 

 represented, although I have not as yet been able to detect dif- 

 ferences enough in the cells to separate the preparations into two 

 groups. 



Despite the uncertainty regarding the exact character of the 

 material, it is clear enough that it is not from H. speciosns, so that 

 we know that any differences manifest in the cells will be between 

 speciosus, definitely identified and described above, and either 

 t'iridis or pratensis. From this comparison it is interesting to find 



FIG. 7. A polar view of the second 

 spermatocyte of Hesperotettix containing 

 the accessory chromosome "<7.r." It 

 forms the smaller half of the tetrad. Not 

 all the chromosomes present. 



a.c. 



FIG. 8. Fragment of a second sper- 

 matocyte pf Hesperoteitix in metaphase 

 showing the tetrad containing the acces- 

 sory chromosome and two ordinary chro- 

 mosomes. 



that there are constant differences in the germ cells which are 

 correlated with constant differences in body structures. So far I 

 have made no attempt to trace variations beyond those shown by 

 the hexad multiple chromosome. Even here only a start has been 

 made, but it will suffice for my present purpose merely to show 

 that there are differences between species of a genus in germ cell 

 architecture. 



First we must notice that there are present in both species 

 multiple chromosomes of the same sort. This must be regarded 

 as a generic character, and for specific differences it will be neces- 



