CYTOPLASM tC INCLUSIONS OF THE GERM-CELLS. 451 
The behaviour of the mitochondrial bodies, their chromo- 
phobe and chroinopliile zones, and the eventual formation of 
the spireme, which is described here in Lepidoptera for the 
first time, have not hitherto been properly examined. 
Munson (6) seems to have been the latest observer to attack 
the problem, but none of the above structures have been 
correctly described. The formation of the acroblastic body 
at the head of the sperm, from the several acroblasts, the 
behaviour of these bodies in division of the cells, are all facts 
which have either been altogether overlooked or incorrectly 
described. The micromitosome has not been traced back to 
the secondary spermatogonium, and the division of the centro- 
some has been overlooked. 
The fate of the middle piece (macromitosome) cannot be 
successfully followed out in later stages in spermatozoon 
formation, and until fertilisation stages have been examined 
after fixation in suitable media, it will be impossible to tell 
whether it even enters the egg. In the same way the behaviour 
of the mitochondria in the egg at this stage will provide 
interesting material for research. It can fairly be stated here 
that it is most unlikely that such a body as the macromitosome, 
bearing in mind its origin and remarkable formation, does not 
enter the egg, for it would then seem that all the complicated 
evolutions of the mitochondria were for nought. Theoretically 
one might suppose that three bodies at least met and fused in 
fertilisation — the pronuclei, the mitochondria, and the micro- 
mitosomata. We know already that the nuclei do fuse, but 
the case of the last two is less certain. In addition, of course, 
one would find observers who would wish to suggest that the 
two cytoplasmas (if the male does introduce cytoplasm) met 
and fused ; but the sperm of the moth is too small for one to 
judge, whether or no, cytoplasm is present in any appreciable 
quantity. 
The acroblasts and mitochondria are bodies of great 
interest; in the newly-formed spermatid it has been shown 
that each half-moon shaped acroblast becomes spherical. 
This evidently takes place by the absorption of a chromo- 
