SPERMATOGENESIS OF ASCARIS 427 
considered to be alike chemically. But with Benda’s stain such 
a misinterpretation could not be made; for the red-brown of the 
karyosome and the karyochromatin is quite distinct from the 
deep blue of the refringent vesicle. 
What then does the use of Benda’s stain teach us concerning 
the material which makes up these vesicles before they appear 
in the late spermatocyte? 
Origin 
There is no trace of this blue-staining material in the cytoplasm 
of the spermatogonium, neither during division stages nor in the 
‘rest stage’ nor yet in the synizesis period. But within the nuclear 
membrane throughout all of these stages a blue-staining material 
is unmistakably present. It is most abundant in the prophase 
of the spermatogonial divisions, where it lines the nuclear mem- 
brane in thin sheets and irregular masses, apparently covering 
the karyochromatin (figs. 2 and 3). Often however the karyo- 
some itself is cut, showing a red-brown color inside, though it is 
covered by the blue staining material. During division this 
material is seen covering the chromosomes. Figure | represents a 
fortunate section of a cell in metaphase in which two chromosomes 
were cut nearly lengthwise. The karyochromatin at the center 
of each is stained red-brown while the surfaces are blue. 
Throughout the synizesis period the chromatic skein is in con- 
tact with the nuclear membrane at many points. As this period 
closes, the greater part of the blue-staining material passes toward 
the nuclear wall, while the karyochromatin and the plastochro- 
matin aggregate to form the karyosome and the plastosome 
respectively. As a rule these bodies take positions near the center 
of the nucleus. 
The young spermatocyte thus shows a fairly definite localiza- 
tion of three nuclear materials, which stain quite differently 
from each other (fig. 4). The migration of the blue staining” 
material does not cease when it reaches the nuclear membrane, 
though as a rule practically all of it has come to line the nuclear 
wall in the form of cords and plates before any of it pushes through 
the membrane into the cytoplasm (fig. 4). In figures 4 and 5 
