514 
somes (heterochromosomes) in certain animals is perhaps just as 
important at this time as evidence of their presence in others. The 
bat testis is a favorable material also for the morphological study 
of mitochondria (chondriosomes; plastochondria-MEvzs). These bodies 
are relatively large and abundant both in the seminal and inter- 
stitial cells. 
Material was collected from June to October. Only by the middle 
of August were spermatozoa being formed. Prior to that time the 
spermatogenetic process halted at early postsynapsis. There are 
present in this young material large spherules of fat of the size of 
individual cells. In the earlier material spermatogonial mitoses are 
abundant; in the later material spermatocytic mitoses of every phase 
appear. All the material was fixed in FLEMMInNG’s fluid, stained in 
iron-haematoxylin with and without counterstain, sectioned at 5 and 
10 microns, jand studied with a Leitz 1/,, objective and a no. 4/,, 
ocular. 
The cells of the bat testis are relatively small. The chromosomes 
also are relatively small, and numerous. The nucleolus of the 
spermatogonial nucleus disappears at mitosis. While the mitotic 
spindles are very clear (figs. 2 and 3), and equatorial sections of 
metaphase plates of chromosomes numerous (fig. 1), it was impossible 
to make an accurate count. The chromosomes are of irregular rod 
form, paired (split) and considerably entangled. There are certainly 
no less than 24. 
The resting primary spermatocyte has a relatively large vesicular 
nucleus with a chromatic nucleolus. The nuclear network is delicate, 
wide meshed, but deep staining. The nucleolus, in contrast to that 
of the spermatogonium and the SERTOLI cell, which is a large spherical 
body with sharp contour, is a more or less irregular central or sub- 
central body. Its contour also is frequently irregular or somewhat 
mossy. Usually it is a slightly elongate bipartite structure (figs. 4 
and 6). Sometimes it is double (fig. 5). It is too regular and too 
constant in respect of presence, location and form to be merely a 
karyosome (net-knot). It is too irregular of contour and shape to be 
a plasmosome. However, on decolorizing to a considerable degree it 
loses the stain; while the synizesis mass of neighboring cells remains 
intensely chromatic. In its tinctorial properties is thus resembles 
somewhat the plasmosome of SERTOLI cells, which destain coincidently 
and approximately to the same degree. Moreover, in destaining, one 
portion of the bipartite body frequently loses its color slightly more 
slowly than the other. But the difference in degree of decolorization 
