onditions in the Coleoptera, so far as the
heterochromosomes are concerned, correspond very closely in final
results with those in the Hemiptera heteroptera and the Orthoptera. In
minor details these chromosomes are less peculiar in the Coleoptera than
in either of the other orders. Even condensation during the growth stage
is not universal, and synapsis of the heterochromosomes apparently
occurs simultaneously with that of the ordinary chromosomes, instead of
being delayed, as in many of the Hemiptera heteroptera.

_Aphrophora_ (Hemiptera homoptera) agrees with the _Anasa_ group of the
Hemiptera heteroptera in having a pair of condensed _m_-chromosomes, in
the growth stage, but this pair is already united in synapsis when first
seen. It differs from _Anasa_, but agrees with _Banasa_ and _Archimerus_
in exhibiting a typical odd chromosome which goes to one pole without
division in the first spermatocyte, and divides with the other
chromosomes in the second spermatocyte. The odd chromosome in this
species of Hemiptera, therefore, behaves like that in the Coleoptera and
Orthoptera. The most interesting points in the results of this study of
the germ cells of _Aphrophora_ is the discovery of two pairs of
condensed chromosomes in certain phases of the growth stages of the
oocytes. This has not been shown to be the case in any other species of
Hemiptera, so far as I can ascertain. It is now evident that in the
Heteroptera homoptera there are at least two distinct classes as to
behavior of chromosomes. In one class we have the Aphids (Stevens, '05
and '06) and Phylloxera (Morgan, '06) in which no heterochromosomes have
been found, while in the other class are such forms as Aphrophora with
both a pair of _m_-chromosomes and a typical odd heterochromosome.

The two species of Lepidoptera examined indicate that here we may have
conditions comparable to those in _Nezara_--an equal pair of
heterochromosomes whose only apparent peculiarity is their condensed
form during the growth stage. Doubtless the results of other
investigators will soon throw more light on the heterochromosomes of
this order.

GENERAL DISCUSSION.

It will be seen from the foregoing that the results obtained in the
study of the germ cells of _Tenebrio molitor_ have been confirmed in
full for several species of Coleoptera, and in part for 19[B] different
species belonging to 8[B] families. It has also been shown that a
different type of Coleopteran s