CYTOPLASMIC INCLUSIONS OF THE GERM-0 EELS. 593 
numerous curved elements as in PI. 32, fig. 25. Moreover, 
the size of the entire spermatocyte, though not of its nucleus,, 
varies greatly (VI, V, V-4). The spermatocytes are either 
crowded as in V-4 to VIII or loose as at V. Crowded sper- 
matocytes have walls like that in PI. 32, fig. 25, etc., loose 
ones like that in PI. 32, fig. 27. Nebenkern in each may be 
the same. The spermatid may be a large vacuolated cell, 
though the sperm has the same end result. 
At the Arabic numerals are drawn all the various genera- 
tions which have male progerminatives which divide to give 
rise to secondary spermatogonia and even tertiary generations 
of spermatogonia. 
At the mid left-hand side at 1 is a primary spermatogonium 
dropping into the lumen. The male progerminative cell at II 
on the right at the Roman numerals is derived from a different 
kind of epithelium with a semi-empty lumen. At 2 (left- 
side) this primary spermatogonium gives rise to many 
secondary cells. Some, as at 2 a, go on dividing till they 
become very small. Others form the bunch drawn at the 
outer middle 2 (Text-fig. 4, iv) . 
By 3 the prophases of the heterotypic division have begun. 
One sometimes finds cells like that drawn at 3 6. Isolated 
cells like this are found in connection with a nurse-cell and 
may form a link between the generations at 1 in Arabic 
numerals and between the other in Roman. These cells, such 
as that at 3 6, seem to be primary spermatogonia which have 
failed to divide but have entered the prophases. 
At 4 are the spermatocytes ; in this generation they never 
vary so greatly as in the generation derived from the epithe- 
lium, as at (I, II, III) or as in the crowded cells. At 5 is a 
first maturation division, which can be compared with the first 
maturation at VI. 1 The spindles are the same size. 
The following indicates where these cells are drawn at a 
higher power : 
1 in PI. 34, fig. 49 (IF.). 
2 in PL 32, fig. 29. 
1 Such cells are not all so large as this example. 
