CYTOPLASMIC INCLUSIONS OP THE GERM-CELLS. 457 
large and not too numerous may finally settle this important 
question. It might be assumed that the spermatocyte mito- 
chondrium divided twice, so that each sperm finally possessed 
a part of the original mitochondrium. From the method of 
distribution of these cell inclusions between the daughter-cells 
I believe that no such mathematically correct division takes 
place in any mitosis, and the slightly varying size of the 
macromitosoine does not give support to this view. 
Summary. 
(1) In Smerinthus populi, Pieris brassicae, and a 
number of other species of moths and butterflies the cyto- 
plasmic bodies have been followed out. 
(2) The micromitosome has been followed from the sper- 
matocyte back into the secondary spermatogonium. It is 
very probably present in the primordial germ-cell. 
(3) The micromitosome has been definitely found in the 
female. 
(4) The micromitosome seems to divide in all divisions, and 
I consider that it is a constant factor in the spermatids of 
Smerinthus. 
(5) The probable nature and function of the micromitosome 
is discussed. 
(6) The mitochondria have been carefully examined in the 
male and female germ-cell in all stages except in the matura- 
tion division of the female and in fertilisation. 
(7) It has been shown that in early stages the cytoplasmic 
bodies of the female resemble those of the male. 
(8) There is a definite period, judged to be about the 
beginning of growth stage, when the subsequent fate of the 
mitochondria in the male becomes different from that of 
the female. 
(9) The remarkable formation of chromophobe and chromo- 
phile zones in the male mitochondrial body and the use of 
these zones are described. 
(10) The formation of the macromitosome from the mito- 
chondria is described. 
