236 WM. REES B. ROBERTSON 



there were several cysts of cells which were in earlier stages than 

 those drawn, probably in Wilson's 'g^ or 'diffused' stage, which 

 is known to follow the approximation stage of parasynapsis, 

 and also because there were no breaks in the stages succeeding 

 figure 165 up to the metaphase. In such a nucleus as is repre- 

 sented at figure 168, I feel still more certain that the gaping 

 apart is the beginning of the disjoining process, because the 

 chromosomes are much farther along in the process of con- 

 densation. I therefore believe that in the gaping apart of the 

 V-bivalents we may have the beginning of the process of disjoining. 



In the rod bivalents of Syrbula (fig. 149) the proximal parts 

 (x, x), which are terminal in this species, are probably in the 

 beginning stages of the process of disjoining. This may be 

 claimed for at least those six bivalents (5, 9; 7, 11 ; and 8, 10) which 

 we have many reasons to believe are the equivalents of the 

 three large chromosomes of Chorthippus (fig. 168). The be- 

 havior of the remaining five bivalents of figure 149 is similar to 

 that of the larger bivalents, and therefore they are probably 

 undergoing the same process. 



First maturation chromosomes, which are probably in the end 

 stages of approximation, some of them possibly in the beginning 

 of disjoining (Schreiners, '06a, fig. 30), behaving like the 5-9 

 7-11, and 8-10 compounds of Chorthippus (figs. 163 and 165), 

 have been described in the work of the Schreiners ('06a, figs, 

 22, 30; '08, figs. 16-18) for Tomopteris. Later stages shown 

 in Salamandra (the Schreiners, '06b, figs. 12-14) are undoubtedly 

 in the disjoining process. The gaping loops of their figures 

 16 to 18 ('08) are almost duplicates of 7-11 's and 8-10's in my 

 figures 163 and 165. Their figures 16 and 17 show, in addition 

 to the loop, the halves of which gap apart in the middle, a short 

 rod with halves gaping apart at the end. This I assume to be 

 a rod pair; the side-to-side approximation, having started at 

 the distal ends, is progressing toward the proxunal ends, which 

 in this case are free (not attached to another rod) and thus form 

 a V. The large-loop chromosome in the same cell is possibly 

 in the same condition. 



I may assume, then, that in my figures of the 'h' stage parasyn- 

 apsis has taken place, since they are so much like those which 



