10 
SPERMATOGENESIS OF NORMAL 
ally increases in size till it becomes a well defined area (Fig. 
3, i). At first it seems to be entirely granular in nature, but 
later displays^ at least in part, a fibrous or reticular structure. 
Near the center of the mass is generally a clear area in which 
a minute centrosome is discernible. As the sphere itself be¬ 
comes better defined, the centrosome appears larger and the 
clear area more distinct (Fig. 3). 
A sphere is often seen in the young spermatogonia just be¬ 
fore division when they are still lying far apart; but, it, as well 
as the nucleus, seems to differ from the sphere and nucleus 
that make their appearance just before the last spermatogonial 
division, subsequent to which the resulting cells undergo a 
period of growth to become the primary spermatocytes. Dur¬ 
ing this last nascent period, the sphere is very large in propor¬ 
tion to the cytoplasm and lies typically on the side of the nucleus 
next the tubule wall. Not only the cells which have divided off 
towards the lumen of the tubule form spermatocytes; those 
which have remained next the wall may double out toward the 
lumen of the tubule, increase in size, and also develop into 
primary spermatocytes. Rarely they remain in place; in such 
an event, one finds the primary spermatocytes and ultimately 
the spermatids, next the wall of the tubule. 
In the resting condition of the spermatogonial nucleus, the 
chromatin is visible ordinarily as small, deeply stained granules 
distributed along the nuclear membrane, and upon the loose 
network which extends throughout (Fig. 3). The granules 
along the periphery are the smallest. There are usually from 
one to three or four chromatin masses or chromatin nucleoli of 
varying size, present at or near the center of the nucleus. 
There is frequently discernible a distinct clump of material 
in the nucleus which reacts to stains in the same way as the 
linin and which may perhaps be considered as an achromatic 
nucleolus. It seems to be in direct continuity with, in fact a 
part of, the linin (Fig. 3, 1.) McGregor^ has made a similar 
observation in the spermatogonia of Amphiuma. In the 
pigeon, when the saffranin gentian-violet method is used, both 
the linin and the nucleolar-like mass take the same bluish violet 
color; likewise, both react similarly to Bordeaux red. The 
1, McGregor, H: “The Spermatogenesis of Amphiuma.”—Joum. Morph. 
XV., Suppl., 1899. 
