cond
division all of the chromosomes are divided quantitatively as may be
seen in figures 77 and 78. A few dividing male somatic cells were found
in the walls of the testis. Figure 57 (plate IX) is an equatorial plate
from one of these. The chromosomes are like those of the spermatogonia
(figs. 58 and 59), 15 large and 1 small. No dividing female somatic
cells were found.

A few drawings of developing spermatids are given to show the
transformations of a peculiar body which seems to be characteristic of
insect spermatids. Figure 79 is a very young spermatid showing only
diffuse chromatin in the nucleus. The nucleus soon enlarges (fig. 80)
and a large dense body (_n_) appears which stains like chromatin with
various staining media. A little later (fig. 81) the chromatin forms a
homogeneous, more or less hemispherical or sometimes crescent-shaped
mass which stains an even gray in iron-haematoxylin. In addition the
nucleus contains a body (_n_) smaller than in the preceding stage, but
staining the same. As the nucleus condenses and elongates to form the
sperm head, a light region containing this deeply staining body is seen
on one side (figs. 82, 83). A little later the body is divided into two,
which appear sometimes spherical (fig. 84), sometimes elongated (fig.
85). As the sperm head elongates still more, approaching maturity, these
bodies diminish in size (figs. 86, 87) and ultimately disappear. A cross
section of the sperm head at such a stage as figure 87 shows the
chromatin in crescent shape with material which stains very little
within (fig. 88). The chromatin-like body described above was observed
in _Tenebrio_ in a stage corresponding to figure 81, and it was thought
that the larger body seen in some cases and the smaller one in others
might be the larger and smaller heterochromosomes, but a study of this
element in more favorable material disproves that supposition by showing
that the different sizes are merely different phases in the evolution of
the body. Throughout its history it stains like dense chromatin, and my
only suggestion as to its origin is that it seems, from a study of this
and other species of beetles, to be a derivative of the chromatin of the
spermatid, increasing in size for a time, then decreasing, and finally
breaking up into granules and dissolving in the karyolymph. Whether it
has any function connected with the development of the spermatozoon, or
whether it is merely material rejected fro