Spermatogenesis in spiders. 521 



real. It is not possible to give a table sliowing- the ratio of the 

 two types of the primary spermatocyte cells, yet extended obser- 

 vations have lead me to think that cells bearing- the ctetosomes are 

 as numerous as those which lack these bodies. This is, of course, 

 what we should expect if the ctetosomes of the last spermatogonial 

 division failed to divide. 



Leptotene-th read period. As the rest period goes forward 

 we find the nucleus taking the stain more deeply and the autosomes, 

 which during the period have been ditfuse and faintly staining, 

 begin to collect into chromatin knots (Figs. 21 to 23). This collecting 

 or condensation of the autosomes goes on rapidly until the whole 

 nuclear cavity is filled with chromatin masses (Fig. 24), which have 

 more or less irregular outlines and wiiich are connected by very 

 fine linin threads. This primary spermatocyte stage is very similiar 

 to the prophase stage for the spermatogonial cells shown in Fig. 1 , 

 except for one point. In the cells of the later period we always 

 find the accessory chromosome present as a very densely staining 

 mass or else as two very distinct nucleoli conspicuous because of 

 their regular outline (Fig. 24 A). In the spermatogonial prophases 

 no such body has been found. The point is of some value because 

 it very often happens that these two stages lie very close together 

 in the testis. 



The individual chromatin knots are distributed on linin threads, 

 and repeated counts have shown that they are present in approximately 

 the same number as the spermatogonial autosomes. The chromatin 

 knots undoubtedly represent the latter bodies at this time. During 

 this period no trace of the ctetosomes has been found; if present 

 they would probably be hidden by the chromatin masses. 



The leptotene-threads, shown in Fig. 26, arise from the 

 chromatin masses described above, but the process goes on with such 

 rapidity in Maevia vittata that the transition stages are rare and 

 hard to interpret. Wilson (Study VIII) has described the process 

 as being an unravelling of the leptotene threads from these chromatin 

 knots. No stages similiar to those figured by Wilson have been 

 found. In Maevia, apparently, we have an intermediate stage (Fig. 25). 

 From the chromatin masses of the latter the leptotene-threads seem 

 to arise. Individual threads have been observed to arise from 

 single chromatin knots and in such cases the free end of the thread 

 was very much twisted. Whether or not we interpret this twisted 

 condition as being a process of unravelling or whether we regard 



