572 
J. bront£ gatenby. 
be difficult to detect, and sometimes two other bodies of a 
larger nature can be found. One, marked X.N.K., may be 
the Nebenkern, but it is too small to be easily made out ; the 
other is a large granule (S.G.), the history and fate of which 
has been so ably described by Bolls Lee ( 9 ). Suffice to say, 
this body is quite definitely seen in Flemming-fixed material 
stained in iron alum haematoxylin, and persists for a long time 
in the sperm cycle. The chromosomes in these divisions are 
seed-like, slightly elongate, and much crowded. There are 
considerably more than forty, and the correct number seems 
to be forty- eight. As far as I can tell, the mitochondria in 
this form of spermatogonial division do not alter in shape 
during kinesis. In PI. 32, fig. 29, I have drawn a spermato- 
gonium just after division has finished and when the nucleus 
is properly reformed. At S.B. is a spindle bridge, at S.G-. a 
siderophilous granule, towards one side of the nucleus the 
small mitochondria are grouped into a conical heap, and 
finally floating free in the cytoplasm is an apparently serrate 
elongated body so plain and large as to be easily drawn in 
with the camera lucida ( N.K . ). I feel quite sure that this is 
the Nebenkern. When the spireme appears and the loops 
become grouped to form the contraction figure the Nebenkern 
takes up its position where the centrosome is known to be in 
other cases. It should be stated that in the best preparations 
I have, one is unable to see a centrosome at any stage until 
near the maturation divisions. In PI. 33, fig. 30, the Neben- 
kern (N.K.) appears to be broken into pieces but still has the 
elongate rectangular shape. The mitochondria are now 
becoming more loosely disposed, aud by the stage drawn in 
PI. 33, fig. 31, are larger and dispersed throughout the cyto- 
plasm. The Nebenkern is now quite distinctly formed of a 
number of tiny intensely-staining rodlets. 
By the end of the growth period the Nebenkern (PI. 33, 
fig. 32) is seen to consist of elongate, slightly curved rodlets, 
somewhat irregularly disposed, but often placed end to end, 
as shown in the spermatid in PI. 33, fig. 35. 
These rods are most easily described as banana-shaped. 
