230 
J. F. Mc Clendon 
The primary germ cell is separated at the fifth cleavage of the egg 
at the ventral edge of the blastophore. It and its descendants may be 
distinguished by their position in the embryo and slow rate of di^ision. 
Wlien the germ cells have increased to foiir, they migrate to the defini- 
tive Position of the gonads and continue to multiply, but the sex cannot 
for some time be distingnished. 
Spermatogenesis. 
Tn the former study of the spermatogenesis I was chiefly interested 
in tracing the development of those „spennatids“ which do not become 
sperniatozoa, but are transformed into food reservoirs by the accuniu- 
lation of plastic products within the nuclei. In the present account the 
history of the chromatin will be chiefly considered. 
The spermatogonia are polyedral cells containing large nuclei the 
chromatin of which exists in the form of a reticulum associated with one 
or more plasmosomes. Düring mitosis sixteen chroniosomes may be coun- 
ted, all of which are apparently equal in size. 
The primary sperrnatocytes are smaller than the spermatogonia but 
have at first a somewhat similar arrangement of chromatin, fig. 1. If 
plasmosomes are present they are too small to be distinguished from 
the chromatin reticulum. The chromatin reticulum sooii begins to con- 
dense into slender filamentous chroniosomes giving the typical lepto- 
tane stage, text fig. It is to be expected that some of the filanients 
might be in contact when first formed, and such seems to be the case, 
but I have never been able to persuade myself that they ever constitute 
a continuous spireme such as has often been seeii in nuclei. Fig. 2 
represents an optical section showing the sixteen filaments. Erroneous 
impressions may easily result from a study of optical sections, and I do 
not present this as evidence of the number of filaments, which I have 
determined by a careful study of whole nuclei, but such a figure gives 
a better idea of the appearance of the filaments. 
The filaments bunch up in the synezesis stage and at the same time 
become straighter, figs. 3 — 6. For this reason the chroniosomes of this 
species are more favorable for study at this particular stage than those 
of the free swimming copepodsi). Düring the synezesis stage parallel 
synapsis takes place, i. e. the chroniosomes become associated in paü's 
with the members of each pair parallel, figs. 3 — 5. The synezesis zone 
occupies a considerable part of the testis. I have sectioned and studied 
1) Cf. Ler.\t: La Cellule, 1905, XXII, p. 161. 
