THE SPERMATOGENESIS OF ONISCUS ASELLUS 
LINN, WITH ESPECIAL REFERENCE TO 
THE HISTORY OF THE CHROMATIN. 
M. LOUISE NICHOLS. 
Tuis study was begun in February, 1899, and finished in 
January, 1901. Its more important results are described in 
this paper. A more complete and detailed account of the 
spermatogenesis will appear in 
a later publication. X 
EA. 
LS A 
. STRUCTURE OF THE TESTIS. Py SI 
© 
= 
OD 
Each one of the two testes leo 
consists of three narrow lobes, F CT eese 
isti V J COS 
distinct from one another and goo Oc 
ois 
{os 
3 
opening successively into the 
anterior expanded portion of 
the vas deferens. The interior 
t each lobe or follicle is occu- 
pied by the germ cells, which : 
are in differing stages of devel- 
opment in the three follicles of 
one side. | Each follicle may 
be divided into two principal 
regions of growth, composed of 
cells of different generations and 
of differing degrees of develop- 
ment. The illustration (Fig. Dm 
will make this clear.1 Itshows, | 
in a typical case, the compara- 
hai degrees of development to whi 
follicles have attained. Thus, in the most posteri 
1. — Testis of Oniscus asellus = * b, 
e 
G. 
ollicles of testis; vas terior part vas de- 
f c 
an 
? . 
erens; f.c., follicle cells; s42, spermatogonia. 
ch the cells of the three 
or of the 
! This and the following figures are slightly schematic. 
: 919 
