DAVIS: SPERMATOGENESIS. 79 
3. GROWTH PERIOD OF THE PRIMARY SPERMATOCYTES. 
A. Diaissosteira carolina. 
1. Autosomes. 
Immediately succeeding the telophase of the last spermatogonial 
division the chromatin becomes diffused throughout the nucleus in 
the form of irregular granules suspended in the linin network (Plate 
2, Fig. 26). At intervals the granules may be aggregated into clumps, 
which are often of considerable size. ‘his stage, which marks the 
beginning of the primary spermatocytes, is, 1 believe, comparable to 
the resting stage of the spermatogonia. 
For the sake of convenience in describing the history of the pri- 
mary spermatocytes it has seemed desirable to distinguish ten quite 
well marked stages, of which the condition described above is the 
first, or stage a. 
During the telophase of the last spermatogonial division and the 
early part of stage a the chromatin is often shrunken away from the 
nuclear membrane forming a deeply staining mass eccentrically placed 
within the nucleus (Figs. 24, 25). Such a condition evidently corre- 
sponds to that first described by Moore (95) to which he applied the 
term ‘‘synapsis.” Similar appearances have been described by a 
number of later writers on spermatogenesis, but, usually, there seems 
to be more or less uncertainty as to whether this condition is normal. 
At first I was inclined to believe that this is a normal stage which lasts 
but a very short time, since cells in this condition occur quite commonly 
during the late telophase and beginning of stage a, but at no other time. 
However, a more careful study has convinced me that such a condition 
of the chromatin is, in reality, an artifact. I am led to this conclusion 
more especially by the fact that in almost every case the cells of the 
peripheral layer, which are in contact with the follicular wall and thus 
in the most favorable position to be acted on promptly by the fixing 
agent, show no such contraction of the chromatin. It is, however, 
undoubtedly true that at this stage, and at no other, the chromatin 
shows a marked tendency to contract away from the nuclear membrane 
if not properly fixed. | 
Stage a is quickly followed by stage b (Fig: 28), which is character- 
ized by the collection of the chromatin into more or less definite, elong- 
ated masses. These masses are connected with one another and with 
the nuclear membrane by fine linin fibrils and have, in general, the 
