pair holds the stain more tenaciously than
the others and also than its smaller mate, and this is true in several
cases where the heterochromosome is smaller than the other chromosomes,
which destain more readily. The odd chromosome of the Elaters stains
less deeply than the others in the first spermatocyte. In the growth
stage they stain more deeply, as a rule, than the spireme, with
iron-haematoxylin or thionin, stain red with safranin-gentian and green
with Auerbach's methyl green-fuchsin combination.

(7) _Aphrophora quadrangularis_ agrees with the _Anasa_ group of
Hemiptera heteroptera in having a pair of _m_-chromosomes and an odd
chromosome in the spermatocytes, but differs from many of that group in
that the odd chromosome divides in the second mitosis instead of the
first. It also differs from other known forms in exhibiting
heterochromosomes in certain stages of the oocytes.

(8) The two species of Lepidoptera examined have an equal pair of
heterochromosomes.

FOOTNOTES:

[A] AUG. 20, 1906.--Since this paper was prepared, 19 other species of
Coleoptera have been studied. Of these, 17 have an unequal pair of
heterochromosomes in the spermatocytes. Six belong to the Chrysomelidae,
making 14 of that family that have been examined. Representatives of 4
new families--Melandryidae, Lamiinae, Meloidae, Cerambycinae have been
studied. In only two species--1 Elater and 1 Lampyrid--has the odd
chromosome been found in place of the unequal pair. No species of
Coleoptera has yet been examined in which one or the other of these two
types of heterochromosomes does not occur in the spermatocytes. Of the
42 species of Coleoptera whose germ cells have been studied, 85.7 per
cent are characterized by the presence of an unequal pair of
heterochromosomes in the male germ cells, 14.3 per cent by the presence
of an odd chromosome.

COMPARISON OF RESULTS IN DIFFERENT SPECIES OF COLEOPTERA.

In number of chromosomes there is great variation, the smallest number
(16) having been found in _Odontota dorsalis_, and the largest (40) in
_Silpha americana_. The difference in size is also very marked, as may
be seen by comparing the spermatogonial plates in figures 3 and 58 with
those shown in figures 94 and 141.

No other species of the Tenebrionidae has yet been secured, and all of
the other beetles examined differ in a marked degree from _Tenebrio
molitor_ in the growth stages of the spermatocytes. While in _Tenebrio_
the