370 EDMUND B. WILSON 



from each of these masses, and concludes that each of the latter 

 thus " becomes converted into a single chromatin- thread." A 

 study of McClung's preparations, particularly of Achurum, leads 

 me to a confirmation of this conclusion. Stage b is better seen 

 in the slides of Phrynotettix than in Achurum; but as the latter 

 shows the unravelling stages more clearly a figure of Stage b from 

 this form is here given (fig. 88). In Achurum the unravelling 

 process is quite unmistakable (figs. 89 to 92, less highly magnified 

 than the other figures of the plate; see also photo. 28). The 

 threads here form closely convoluted knots (much like those 

 figured by Janssens in the spermatogonial prophases of Triton), 

 and a spiral arrangement is seldom seen. In Phrynotettix and 

 Mermiria the process is less evident, but appears to be of the same 

 general nature. 



Especially in Largus, Anax and Achurum the definiteness of 

 the pictures and the succession of the stages seen side by side in 

 the same cysts or in adjacent ones, entirely excludes, I think, the 

 possibility that they are a merely accidental appearance due to 

 vacuolization of the massive bodies, corrosion-products or fixa- 

 tion-artifacts. The only question is whether the thread that 

 unravels from each massive body is single, double or longitudinally 

 divided. I am nearly certain that the threads are single and undi- 

 vided. In this respect my conclusions agree with those of Davis, 

 and differ from those recently announced by Brunelli ('11) in the 

 case of Tryxalis. This author describes a similar unravelling proc- 

 ess but believes the threads to consist of two separate longitudinal 

 halves which result from a longitudinal split that is evident already 

 in the preceding telophases, and which separate still more widely 

 as they uncoil. The evidence for both these conclusions seems to 

 me very incomplete, as none of the unravelling stages are shown, 

 and the massive bodies of Stage b are assumed to arise directly 

 from the telophase chromosomes without proof of this impor- 

 tant point. This assumption may be correct, but it seems more 

 probable that Stage a has been overlooked by this observer. 



The question here involved is so important that I have en- 

 deavored to reach a more certain result by study of the analogous 

 processes seen in the spermatogonial prophases. The first of these 



