372 EDMUND B. WILSON 



the thread-formation is preceded by a stage in which the chro- 

 mosomes appear in the form of deeply staining, elongated, and 

 more or less definitely polarized bodies (fig. 93, photo. 29), ragged 

 in contour and loose in texture, but showing as yet no definite 

 coiled thread. This condition must shortly precede the thread- 

 formation because the latter may clearly be seen in other nuclei 

 in the same cysts. Whether these bodies are individually derived 

 from the anaphase-chromosomes of the preceding anaphase can 

 not here be determined, but Miss Pinney's observations make it 

 highly probable that such is the case. In any case, already in 

 the early prophases each of these masses is seen to be resolving 

 itself into a closely coiled or convoluted thread, similar to that 

 seen in the pre-synaptic stages but disposed in more definitely 

 spiral fashion (figs. 94 to 96, photos. 30 to 32). In some cases 

 there are indications that each of these spirals is still enclosed in 

 a more or less separate nuclear sacculation, in other cases this 

 can not be seen. In some cysts the threads are seen tightly 

 coiled within the massive bodies at one side of the cyst, while 

 stages of uncoiling are seen progressively towards the opposite 

 side. In slightly later stages all gradations are seen in the uncoil- 

 ing of the threads to form separate threads, which still show a 

 distinct spiral course even after they have begun to shorten and 

 thicken (fig. 96, photo. 32). From this stage it is easy to trace 

 every step up to the time when the prophase-chromosomes are 

 about to enter the metaphase. The longitudinal division is not 

 evident until the uncoiling is well advanced, and the two halves 

 remain in close apposition until the metaphase. 

 The points that I would here emphasize are : 



1. The extreme clearness with which the spiral threads are 

 seen, which removes every possible doubt as to what is taking 

 place. 



2. The fact that the threads are separate from the time of 

 their first formation. Apparently there can be no question here 

 of a -continuous spireme. 



3. The transitional conditions seen in the same cysts, which 

 prove these stages to be prophases, not telophases. In this re- 



