515 



of any longitudinal split in the spireme, which simply divides trans- 

 versely into seven segments (one half the somatic number), and there 

 is no formation of tetrads. In the first division these segments are 

 divided transversely, and in the second, the daughter segments are 

 again divided transversely. Both divisions are therefore reduction 

 divisions, as maintained by Wilcox, though they occur in a slightly 

 different way. 



The results at which I have arrived in a study of the spermato- 

 genesis in the Hemiptera, difter entirely from those of Wilcox and 

 Montgomery and agree in principle with those of Vom Rath. My 

 work has been upon several species but in one only has the process 

 been entirely followed. In the other cases it has, however, been car- 

 ried far enough to justify the statement, that in a number of species 

 of Hemiptera, there is a distinct longitudinal split at an early stage 

 of the spireme, though it afterwards becomes masked by the great 

 breaking up of the chromatin. At a later period, a tetrad is formed 

 by two divisions at right angles to each other, one of them being the 

 original longitudinal splitting of the spireme segment. Thus only 

 one of the subsequent divisions is reducing, the other being an equa- 

 tion division. 



The greater part of my material was fixed in Hermann's fluid 

 and stained with Heidenhain's iron ha^matoxylin , these methods 

 giving the best results. 



In Anasa tristis de G. where the entire process has been 

 followed, we find that after the last spermatogone division, the chro- 

 matin collects at one side of the nucleus as a mass of irregular 

 threads, forming the synapsis stage of Moore. As the chromatin 

 emerges from this stage, it can be seen to consist of a number of 

 short segments each of which is split longitudinally (Fig. 1). Though 



Fig. 1. 



Fig. 2. 



Fig. 4. 



t is impossible to count them exactly at this time, their number is 

 certainly less than it was in the spermatogones and from their later 



