WILCOX: SPERMATOGENESIS. 5 
(2) after staining, (3) after decolorizing. Simple immersion in water 
does not do as well The mordant and stain will form a precipitate, 
just as in Henneguy's method, and if the first washing be negleoted, it 
is next to impossible to remove the precipitate by subsequent washings. 
One to five minutes in a stream of water is enough for each washing. 
The sections will become quite opaque immediately after immersion in 
the decolorizer, but in this the opacity is slowly removed. The decolori- 
zation is hastened by washing the sections in water at intervals during 
the process of decolorizing. This is necessary, also, in order to see how 
far the decolorizing has progressed. The process can thus be stopped 
at the desired stage. The proper decolorization is the most difficult 
part of this method. 
By the “blue” process, so far as ny experience goes, the cytoplasm 
stains gray, the centrosomes do not stain at all, the spindle and linin 
fibres very faintly, the chromosomes dark blue. By the “black” pro- 
cess the cytoplasm takes a dark-gray color, and both centrosomes and 
chromosomes are made black, while spindle fibres aud linin fibres be- 
come very distinct. The nucleoli are colored nearly black by either 
process. 
CICADA TIBICEN. 
The testes of Cicada tibicen are paired, and each consists of a large 
number of ellipsoidal follicles, which are closely packed together. The 
follicles of cach side of the body open into a vas deferens, which soon 
joins its fellow of the opposite side. Figure 14 (Plate I.) gives an idea 
of the spatial relationship to one another of different spermatogenetie 
stages. It represents a very nearly longitudinal section of a follicle of 
Cicada. At a are spermatogonia; at d, spermatids in various stages of 
metamorphosis. 
The Cicada material at my command did not show the division stages, 
but it gave a very reliable series of preparations on certain other stages. 
The spermatogonia lio at the blind end of the follicle. They occupy 
in my preparations only the single end-compartment (Fig. 14, a). Their 
size is less than that of the spermatocytes, and they are further distin- 
guished from them by the fact that they have only 12 chromatic rods, 
whereas the spermatocytes have each 24 spherical chromosomes. One 
or often two nucleoli are to be seen. 
The spermatocytes ocoupy usually two compartments next to that of 
the spermatogonia. The chromatic substance consists of about 24 
