138 
ON THE SPERMATOGENESIS OF THE SILK-WORM. 
change so as to form a granulated ball with a free plasm around 
them (tig. 62 d, n). Along with these changes, the chromosomes 
gradually separate from one another and arrange themselves at 
the periphery of the nucleus. Figs. 63 and 64 are drawn from 
fresh specimens treated with acetic acid methyl-green. Chromo¬ 
somes collect near the nuclear wall and present a moniliform 
appearance in a side view. The fully grown “Nebenkern” (n) 
and mitosomes (in) are seen, one of the latter surrounded by a 
free plasm. In fig. 64 beside the “ Nebenkern ” and mitosomes, 
a row of microsomes is to be seen running through the axis of 
the tail. A further stage with a more elongated head and a 
pretty long tail is represented in figs. 65-83. 
In fig. 65 is given the head of a spermatozoon at a some¬ 
what advanced stage. Chromosomes are as in the first stage 
arranged at the periphery of the nucleus, while the “ Neben- 
kern ” appears more compact than before, slightly presenting 
its granular structure. The position of mitosomes is very irregu¬ 
lar, being placed either below or above the “ Nebenkern ” (figs. 
65, 66 b, 68, 70, 71). 
Sometimes we see that it is situated at the extreme point of 
the head of a spermatozoon anterior to the nucleus (fig. 67 m). 
Beside these structures there are to be seen some other 
granulated spots, which are sometimes coagulated into a single 
mass, sometimes scattered more irregularly (figs. 65, 68, 71, 
72). These phenomena are very similar to those described by 
Henking in Pyrrhocoris (25). Gradually these “Nebenkern” 
elongate into the structure of the tail-part (figs. 68, 69, 70, 71, 
72, n). In the cross section of the tail passing through the 
“ Nebenkern” of this stage, radial processes are seen from the 
“Nebenkern” to the wall of the tail of the spermatozoa (fig. 
70 b, 1-2). 
The “Nebenkern” elongates more and more, becoming thin¬ 
ner, and with this change, the mitosome gradually becomes fainter 
and smaller. The radial processes of the “ Nebenkern ” disappear 
(figs. 73, 77). In fig. 73 a cross section of the median part of 
the tail with a “ Nebenkern ” in the centre of it, is represented. 
Hand in hand with this change, chromosomes gradually 
accumulate at the one side of the periphery of the nucleus. This 
accumulation presents a somewhat crescent shaped figure, but the 
