196 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
Nebenkern is now seen to be a spheroidal body, in which all traces of 
a fibrous condition are lost. It lies close by or applied to the nucleus, 
having the centrosome between it and the nucleus. The Nebenkern 
now elongates and forms the axial portion of the tail of the spermato- 
zoon (Plate 3, Figs. 87-89). 
From Figures 111-114, which are drawn from a preparation of the 
testis of Trirhabda tomentosa, one of the Chrysomelide, it is readily 
seen that the relationships and fate of the nucleus, the centrosome, and 
the Nebenkern are essentially the same as they are in Caloptenus. 
The body which appears in the vacuole of the nucleus (Figs. 94-98) 
is rather problematical, both as to its origin and its fate. It appears 
usually as a rod of deeply staining substance, whose longest axis is in 
the long axis of the vacuole ; but the rod may have the form of a cres- 
cent (Fig. 95). 
The tentative conclusion to which I have come with regard to this 
body is, that it represents the nucleolar substance of the nucleus of the 
spermatid, and that it subsequently passes into the mass of chromatin, 
with which it becomes homogeneously mingled. My evidence for this is 
as follows. Very soon after the second division of the spermatocytes 
a body is seen in the nucleus, which is quite distinct from the rest of 
the stainable substance of the nucleus (Plate 3, Figs. 77, 78, 83, 85). 
It (cres.) lies at first among the chromatic granules of the nucleus, but 
is distinguishable from any of the latter by its greater size and deeper 
color (Figs. 57, 102-104). Them it comes to lie in the vacuole of the 
nucleus (Plate 3, Figs. 94-98). At length, what I consider its remains 
are found for some time faintly discernible in the chromatic mass of the 
head of the immature spermatozodn (Figs. 88 and 106-108). In later 
stages (Fig. 110) this body is not to be distinguished from the rest of 
the chromatic mass. I was at first inclined to believe that this body 
allied itself with the centrosome to help in forming the neck-body, but 
was soon convinced that this is not true, because I observed that the 
two parts of the centrosome and this problematical body exist at the 
same time in the same spermatid (Figs. 97, 98). In Figures 90, 92, and 
106 the body in question is seen in contact with the chromatic mass, 
and in Figures 103, 104, it is nearly included in the chromatic crescent. 
Later, as already indicated, it becomes indistinguishable from the rest of 
the head of the spermatozoén. Accordingly, Iam unable to determine 
whether or not it forms any definitely limited portion of the head. 
At the time when the two daughter cells separate from each other at 
the conclusion of the second division of the spermatocytes, the chromatic 
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