CYTOPLASMIC INCLUSIONS OP THE GERM-CELLS. 423 
but I do not believe mitochondrial bodies of the spermatocyte 
will be found specifically different enough to distinguish 
satisfactorily genera, families, or even, sometimes, orders of 
Lepidoptera. Exceptions to this may be found ; for instance, 
one could easily distinguish between Orgyia and Pieris, apart 
from other cell peculiarities in the two examples, by means of 
their mitochondria, but in all probability Orgyia antiqua 
and Orgyia casnosa would be just as much alike as the two 
Pierids mentioned in this paper. Then, too, it should be 
noticed that the Sphingidae (represented by Smerinthus) have 
the same type of mitochondrial body as the Pieridas — two 
families in no way related. Before comparison can be carried 
further, we must have at our disposal more work on the 
subject, and I leave the matter at this point. 
Changes undergone by Mitochondria in the Sper- 
matocyte. 
The mitochondrial bodies never remain unchanged. They 
are able to move about in the cytoplasm, probably being 
carried by cytoplasmic currents. But there are other facts to 
be noticed. Near the end of the growth stage, and thence- 
forth, one often finds that several mitochondria have coalesced 
or run together and form a single, very large body as shown 
in PI. 23, fig. 11, V.V., and PI. 25, figs. 32, 33, 34, and 43. In 
such cases I believe the running together may be caused by 
the close contact and subsequent fusion of the outer rim of 
the body, and the final flowing together of the chromophobe 
fluid core of adjacent mitochondria. It is often found that 
the mitochondria, where they are densest, run together to 
form cords or filaments, as shown in PL 25, fig. 31, and there 
is some probability that these large mitochondria and fila- 
ments are caused by the fixative. In my material of Vanessa 
fixed in the bulk in Regaud solution the mitochondria are 
bead-like, as is usually the case ; in smears fixed previously 
in osmic vapour and then soaked in Regaud solution the 
mitochondria are filamentous, or apparently a solid mass. It 
