of the spermatid showing the chromatin
nucleolus (_n_) in various phases.

Blepharida rhois (Family Chrysomelidae).

The testes were rather too far advanced when this material was collected
and no dividing spermatogonia were present. The growth stages (figs.
131, 132) show a faintly staining spireme and a heterochromosome group
similar to that of _Odontota_, a large and a small chromosome attached
to a large plasmosome. The spireme appears to go directly over by
condensation and segmentation into the dumb-bell-shaped figures seen in
the first maturation spindle (figs. 133, 134), though cross-shaped
bivalents occasionally occur (fig. 135). The heterochromosome pair,
slightly separated by plasmosome material, is usually found at the
periphery of the plate (figs. 133-136). Figure 137 is an exceptional
anaphase in which the heterochromosome elements are not mingled with the
polar masses of chromatin. Figures 138 _a_ and _b_ are equatorial plates
of the second mitosis, and figures 139 and 140 are pairs of daughter
plates from second spermatocytes showing again the dimorphism of the
spermatozoa as to their chromatin content. As in several of the forms
studied, material was collected for examination of the somatic cells,
but no favorable cases of mitosis were to be found.

Silpha americana (Family Silphidae).

Only one male of this species was secured, but the large testes gave all
stages in abundance. The chromosomes, however, were very small and too
numerous, 40 in the spermatogonia (fig. 141). The small chromosome is,
nevertheless clearly distinguished in many of these plates (_s_). The
resting spermatogonium contains one very large plasmosome and often one
or two smaller ones (fig. 142, _p_). The unequal pair is seen in the
growth stages (figs. 143, 144), and may frequently be seen outside of
the equatorial plate of the first spermatocyte spindle (fig. 146). In
favorable sections it may also be found in the plate among the other
bivalents (fig. 147). Figure 145 is a prophase showing the bivalent
chromosomes still connected by linin fibers. An equatorial plate of the
first division is shown in figure 148, and a pair of corresponding
plates of the second spermatocyte in figure 149. The small
heterochromosome divides in the second spindle in advance of the others
as seen in figure 150. Therefore, although this form is not especially
favorable for detailed study on account of the large number of small
chromosomes, the