566 
J. BRONTfs GATENBY. 
In the ovotestis of the hibernating snail where activity 
is temporarily suppressed, just as in a summer example 
where activity is very great, it is found that the diverticula 
or alveoli in the hermaphrodite gland almost always are 
better provided with yolk and younger cells at their upper 
extremity than at tlie lower part of the finger-like alveolus 
which joins the mouths of other diverticula. That is to say, 
the higher ones penetrate into the diverticulum, the younger 
and less differentiated are the elements. When one cuts a 
transverse section across the upper part of an alveolus one 
finds that the lumen is very small sind is choked either 
with full yolk cells projecting from the walls, or closely 
packed with spermatogonia and young spermatocytes. It is 
rare to find an oocyte at these places, but it would be a 
mistake to think that oocytes never occur in these regions. 
In Text-fig. 1 is drawn the upper region of an alveolus. 
Just as in the young snails described by Ancel, the first cell 
elements to appear are almost invariably spermatogonia, but 
I have found several instances where an oocyte had appeared 
immediately after the yolk cells had been formed. In Text- 
fig. 1, i, the germinal epithelium has already become 
organised into two layers, an inner mass of yolk cells filling 
the lumen and the lower indifferent germinal cells ( G.E . ). 
At X. a germinal epithelial cell has grown in size, has lost its 
flattened shape and is about to become a spermatogonium. 
In Text-fig. 1, ii, this process has become more advanced and 
the nurse-cells are becoming pressed apart at X. by a number 
Text-fig. 1. 
Fig. i. — Upper part of diverticulum of ovotestis showing yolk cells 
(N.C.) and germinal epithelium (G.E.). At X. are enlarged nuclei, 
which are in a progerminative stage. In the middle are some 
spermatocytes. The vacuolised tissue outside consists of meso- 
derm, which packs around the upper parts of the diverticula. X 800. 
Fig. ii. — Another diverticulum cut near its upper end. At X. are 
some primary male cells which as yet have no definite mitochondria 
or Nebenkern. They will probably become spermatocytes directly. 
At Y. is a pale cell beginning to enter a primary spermatogonial 
stage. Figs, iii and iv are spermatids showing different Xebenkern 
batonettes (N.K.). M 1 . — micromitochondria. M 2 . = macromito- 
chondria. N.C. = yolk cell. 
