430 
J. BRONT& GATENBY. 
envelope of this body. As this goes on the chromophobe 
substance dwindles, and the spireme appears to break up 
partially. In PI. 24, fig. 20, is a fairly late stage. The mito- 
chondrial matter is filamentous, but one wonld hesitate to say 
whether the filaments were intercontinuous. In later stages 
of spermatozoon formation the middle region becomes so 
attenuated that it is quite impossible to say whether or not 
the macromitosome is absorbed or sloughed off. I think that 
the macromitosome does probably persist, but its final fate 
is difficult to ascertain, and I do not regard late spermato- 
genesis stages as suitable material for finally settling this 
point. The obvious course is to examine fertilisation, and to 
follow out the sperm after entry into the egg. Concerning 
these points I shall have a few remarks to offer in the 
discussion (p. 450). 
What I have said under this heading naturally applies ta 
the micromitosome and second eentrosome as well, for all 
attempts at finding either of these structures in the ripe 
sperm have failed. 
It may be that the macromitosome and micromitosome 
resemble the nucleus and acrosome in that they may become 
so condensed as to be easily overlooked, but may, neverthe- 
less, be present, and be carried into the eggs. 
The Micromitosoina of Sinerinthus populi followed 
out in Material fixed in Cliampy. 
In the primary spermatogonium the nucleus always is 
wrapped around, especially on one side, by a half-moon of 
granular substance (PI. 23, fig.^. This semi-lunar shaped 
zone is made up of minute granules quite darkly staining,, 
and as far as one can make out not of the same size ; but by 
choosing favourable examples it is sometimes possible to find 
two other bodies in the cytoplasm, one often quite near the 
nucleus (but almost as often isolated towards one end of the 
cell), which is the eentrosome ; the other distinctly larger and 
staining very sharply, which is probably the inicromitosoma. 
