312 TAKU KOMAI 
advanced developmental stages. Without doubt, this cluster 
represents the proliferating region of the seminal tube. 
A similar arrangement of seminal elements has been observed 
in crabs by Binford ('18) and Fasten (’18). However, in those 
cases, the regions containing younger elements appear in section 
crescentic in outline and restricted to one side of the tube wall, 
whereas, in Squilla, they form complete rings of nearly uniform 
thickness. 
The vas deferens is lined with a rather high epithelium enclos- 
ing large nuclei. ‘The spermatozoa contained in the cavity form 
a compact mass, apparently being agglutinated by some cement- 
ing material. A broad space is often found between this mass 
and the wall surrounding it. 
SPERMATOGONIAL AND NUTRITIVE CELLS 
The transformation stages of the seminal cells up to the pro- 
duction of spermatids have not been traced in detail, so that I 
can give but a brief account of them. The spermatogonial 
cell (figs. 2 and 3) is polygonal and is marked off from its neigh- 
bors by a fairly distinct cytoplasmic wall. It contains a large 
vesicular nucleus, which is usually spheroidal or ovoid. Numer- 
ous chromatin granules of varying size are found in it. <A few 
largest ones, occurring in the central part of the nucleus, repre- 
sent the karyosomes and forms the centers of radiating linin 
strands, along which are arranged smaller and less conspicuous 
granules. 
In the cytoplasm and close to the nuclear membrane, are 
bodies apparently to be identified as the ‘chromatoid bodies’ 
(fig. 2, k). They may be spheroidal, dumb-bell- or spindle- 
shaped and stain in basic dyes as strongly as the chromatin 
granules in the nucleus. Some of them are often so large and 
conspicuous as to be easily detected under low magnification, 
while some may be extremely minute and barely discernible 
with very high power. Small spheroidal ones look more like a 
centrosome, and it is rather hard to distinguish the former from 
the latter. The centrosome (c) is a single minute spheroidal 
body lying close to the nuclear membrane. No idiozome could 
be detected around it. 
