figures will be given here for reference in the general discussion.

METHODS.

The testes were fixed in various fluids--Flemming's strong solution,
Hermann's platino-aceto-osmic, Gilson's mercuro-nitric, Lenhossek's
alcoholic sublimate acetic, and corrosive acetic. Flemming's and
Hermann's fluids followed by safranin gave good results in most cases.
The mercuro-nitric solution and Lenhossek's fluid gave excellent
fixation and were preferable to the osmic mixtures when it was desirable
to stain the same material with iron-haematoxylin, and also with various
anilin stains.

Heidenhain's iron-haematoxylin, either alone or with orange G or
erythrosin, was used more than any other one stain. With osmic fixation
safranin gave better results in some cases, because of the abundance of
spindle fibers and sphere substance which were stained by haematoxylin.
The safranin-gentian combination used by Miss Wallace and others in the
study of the accessory chromosome did not prove to be especially helpful
with these forms. Thionin was found to be a very useful stain for
distinguishing between the accessory chromosome and an ordinary
nucleolus. Licht-gruen was often used in combination with safranin.

RESULTS OF INVESTIGATIONS.

Termopsis angusticollis.

In the termite it was not found to be practicable to dissect out the
testes. The tip of the abdomen was therefore fixed and sectioned, young
males whose wings were just apparent being used. The cells are all
small, and could not be studied to advantage with less than 1500
magnification (Zeiss oil immersion 2 mm., oc. 12).

In the spermatogonium there is a very large nucleolus (plate I, fig. 1),
which in the iron-haematoxylin preparations is very conspicuous, but does
not stain like chromatin with thionin or other anilin stains, nor does
it behave like an accessory chromosome during the maturation mitoses.
Before each spermatogonial division it divides as in figures 2 and 3,
and the same is true for each maturation mitosis. Figure 4 shows the 52
chromosomes of a spermatogonial division in metaphase. Figures 5 and 6
are young spermatocytes, showing the division of the nucleolus. Figures
8, 9, and 10 show a stage immediately following that shown in figure 6
and evidently persisting for some time. The spireme thread is very fine,
stains deeply, and is wound into a dense ball, often concealing one
(fig. 10) or both nucleoli (fig. 8). Figure 11 shows the next stage; the
biva