CYTOPLASMIC INCLUSIONS OF THE GERM-CELLS. 575 
In Pl. 34, fig. 44, at a still later stage, the Nebenkern, 
which hitherto kept its rectangular figure, has become col- 
lapsed by the pressure of the narrowing space in which it lies, 
and its individual parts are better revealed. In some cases, 
at least, it seems that the Nebenkern elements at this stage 
do really enclose an archoplasmic region, or at least a denser 
region of the cytoplasm. In PI. 34, fig. 44, the mitochondrial 
elements are becoming larger, and they now form a rough 
coat to the axial filament. First are seen the micromito- 
chondria, which now form an undoubted covering, while 
behind is generally seen the Nebenkern. Behind this lie the 
macromitochondria, which are less evenly disposed than the 
micromitochondria. By PI. 34, fig. 45, the micromitochondria 
have disappeared as such, but if the axial filament is carefully 
examined, it will be seen that it lias increased both in thick- 
ness or bore, and in its affinity for basic dyes. Followed 
further down to the macromitochondrial region the filament 
gradually resumes its original staining powers and propor- 
tionate size. These areas of the filament are marked X , 
upper, Y, where the intermediate region lies, and Z, lower, 
where there is a slight but hardly perceptible thickening. 
In PI. 33, fig. 37, at a higher power is drawn the front region 
of a metamorphosing sperm just before the stage described in 
PI. 34, fig. 44. The disposition of the elements is quite 
typical, while the Nebenkern is crumpled up and is seen to 
consist of nine batonettes or rods, which together formed the 
rectangular structure drawn in the previous figure (PI. 33, 
fig. 36). In PI. 33, fig. 37, these rods seemed to be sur- 
rounded by a clear zone. 
As metamorphosis goes on the mixed-up macromitochondria 
and batonettes become further and further removed from the 
head of the sperm, while the former of the two become 
somewhat larger and increasingly fewer in number. They 
seem to be absorbed finally into the sheath of the tail, and if 
anything is cast off it must be a very small portion indeed. 1 
1 A residuual bead is always cast off, and it always contains some 
mitochondrial grains. 
