254 
J. 0. Wakelin ßanatt and G. Arnold 
chromosomes of the second maturation division (homotype division, second 
meiotic division). These chromosomes are smaller than the chromosomes 
of the heterotype division and are made np of rounded masses of equal 
size. The second maturation division results in the formation of two 
spermatids (Fig. 10). 
The conversion of the spermatid into the Spermatozoon next takes 
place. The nucleus of the spermatid rapidly enlarges, the cliromatin 
granules become increasingly finer, until finally it presents a more or less 
homogeneous aspect (Fig. 11). In the cytoplasm of the young spermatid 
an archoplasm forms, in which one or more small vesicles appear, which 
become closely applied to the nuclear membrane. These increase in size, 
and eventually fuse to form one large vesicle, in the centre of which 
appears a darkly stained mass, the intermediate substances of Moore 
and Walker 1 ) (Fig. 10). The single vesicle thus formed becomes flattened 
and spreads over one half of the nucleus. At the same time the inter- 
mediate substance, which increases in size, also becomes closely attached 
to and flattened out upon the nuclear membrane. The remains of the 
archoplasm then become lost in the cytoplasm together with the inter- 
mediate substance, (acrosome of Lenhossek). It will thus be seen that 
the archoplasmic vesicle forms a cephalic cap embracing the nucleus 2 ). 
At the side of the nucleus opposite the cephalic cap lie the two centro- 
somes, and in their neiglibourhood the chromatoid bodv is seen (Fig. 10). 
When the cephalic cap has covered one half of the nucleus, a collar like 
structure (manchette), formed from the cytoplasm, appears at the opposite 
end of the nucleus (Fig. 11). It is conical in shape, its base being attached 
to the nuclear membrane, and is only a temporary structure, soon dis- 
appearing. It encloses the two centrosomes and the chromatoid body. 
One of the centrosomes now lies on the nuclear membrane and acquires a 
flattened disc like form (Fig. 12). From the other centrosome the axial 
filament of the tail of the Spermatozoon is developed. While these clianges 
have been taking place in the position and form of the centrosomes, the 
cytoplasm, which has shifted completely to that side of the nucleus which 
is opposite the acrosome, now lengthens out in the direction of the axial 
filament, and little globales of fat appear in it, which increase in size 
and number. The greater part of the cytoplasm, containing the remains 
of the archoplasm, the chromatoid body and the above mentioned globules 
of fat, is next cast off, an exceedinglv small portion remaining round the 
x ) Loc. cit. 
2 ) Cp. Dcesberg (2), Figs. 5 — 9. 
