CHROMOSOMES OF TIGER BEETLES 447 
B. Early spermatogonia 
In the early spermatogonial nuclei there is a fine chromatin 
network, not evenly distributed but more or less in clumps. In 
practically every instance it was either attached to, or most 
abundant near the nuclear wall and had a fibrillar connection 
throughout the nucleus. As the nucleus grows, this network 
becomes. broken here and there, leaving the central area almost 
free from chromatin (figs. 1 and 5). Simultaneously and asso- 
ciated with the breaking of the central network, the chromatin 
aggregations become more conspicuous and come to lie nearer 
to, or in contact with, the nuclear wall. In some instances, 
however, one or more clumps of chromatin remain some distance 
from the nuclear wall, but in all observed cases, they were con- 
nected with this membrane by anastomosing fibrillar bridges 
(fig. 1). Since the small particles of chromatin are also de- 
posited on the nuclear wall, this membrane soon becomes much 
more conspicuous than in earlier stages. The staining capacity 
continues to increase until the nucleus reaches its maximum size 
(figs. 1 and 2). This condition, as well as the formation of the 
spermatogonial chromosomes, is highly suggestive of the con- 
cluding stages of the growth period in the Hemiptera and other 
forms. It is interesting to note that the prophase spermato- 
gonial nuclei are much larger than those in the corresponding 
stage of the first spermatocyte division (figs. 29 and 30). The 
mean diameter in case of the former is lly, while the latter 
measured only about 6u. 
The above chromatin aggregations are further differentiated 
by the smaller particles uniting with them, leaving the inter- 
vening spaces clear. This method of intensifying the nuclear 
wall by the addition of chromatin granules and the disappear- 
ance of it with the withdrawal of the chromatin material again 
suggest that ‘‘this membrane may be, at least in part, chromatic” 
(Goldsmith, ’16 a). . 
The irregular chromatin masses now begin to suggest the 
shape of spermatogonial chromosomes (figs. 2, 3, and 4). These 
more or less definite but granular bodies assemble about the 
