236 MICHAEL F. GUYER. 



in evidence (Figs. 119, 120). Then follow stages in which the 

 stainable content seems confined to a very fine spireme with 

 the chromatin practically all concentrated in the filaments 

 (Fig. 121). In especially favorable preparations it can be seen 

 to be strung along as a string of very small round chromomeres. 

 This stage is evidently the leptotene stage of modern literature. 

 Whether the threads are separate and as numerous as the diploid 

 chromosomes or whether they constitute a continuous or a dis- 

 continuous spireme could not be determined. It can only be 

 averred that the strands are much finer, and more numerous 

 than those which exist just prior to the appearance of the indi- 

 vidual chromosomes. Any number of instances of two of the 

 fine filaments lying parallel one to another could be cited, but 

 whether such threads constitute true pairs in process of para- 

 synapsis or whether the condition is purely incidental could not 

 be determined. Regarding the question of parasynapsis I can 

 only affirm that the evidence is certainly not against such an 

 interpretation and as far as it indicates anything it rather points 

 toward parasynapsis than otherwise. 



Consequent upon the leptotene stages come the contraction 

 phase or synizesis in which the filaments condense into what 

 appears to be an indiscriminate tangle (Fig. 122), and then 

 slowly follows a second extension of the chromatic filaments 

 throughout the nuclear area until the nucleus is occupied once 

 more by a spireme, this time of fewer and coarser filaments 

 (Figs. 123, 124). In Fig. 123, two elongated, nucleolar-like 

 elements are visible. 



The spireme in its various phases is a stage of considerable 

 duration if one may infer from its universal presence in almost 

 any section taken from an active testis. When it once starts to 

 condense into the individual chromosomes the operation, judging 

 by the scarcity of stages to be found, is a comparatively rapid 

 one. Just how the bivalent chromosomes form from the spireme 

 I have not been able to discover despite much time spent in the 

 attempt to do so. One finds a relative abundance of metaphase 

 stages but in every case the chromosomes, when identifiable, are 

 well established, relatively compact bodies. The most diligent 

 search has failed to reveal the accessory chromosome or chromo- 



