342 CHIKANOSUKE OGAWA 
with respect to the capillary networks is that the two layers of 
the capillary networks of Elaphe communicate with each other; 
hence, if capillaries are traced in surface view, they sink to a 
lower level and can be followed through to the capillary layer 
of other side (fig. 6). 
Now we can distinguish also in this animal two kinds of epi- 
thelial cells, namely, small, nucleated cells and large, flat ones. 
The small, nucleated cell is not rhomboidal as in the tortoise, 
but more or less irregular in its shape, though it may be in some 
instances designated as pentagonal or hexagonal; in general it 
belongs to the cuboidal category and is situated mostly in the 
intercapillary spaces. ; 
The large, flat cell is considerably larger than the small cell 
in surface view—more than ten times as large in diameter. 
Although the border lines of the cell are not always rectilinear, 
as is the case in Clemmys, it may be described as approximately 
square or pentagonal. As in Clemmys the nucleus cannot be 
demonstrated by the silver method. Since in Clemmys, rela- 
tively thick blood capillaries lie beneath the flat cells, it happens 
that in sectioning the epithelial cells are separated at certain 
points from the subjacent tissue and consequently the presence 
of the nuclei, which belong to the epithelial cells, can be confirmed 
by staining, but it is not so in Elaphe, because here the flat cells 
are considerably large and cover both the blood-capillaries and 
intercapillary spaces at the same time and sometimes sink more 
or less into the spaces which are fairly wide; hence it is difficult 
to cut off the epithelial cells from the subjacent tissue and to 
decide by nuclear tinction whether or not the stained nuclei 
belong to the epithelium. However, in specimens which have 
been impregnated with silver and mounted, without clearing, 
in such a substance as Japanese millet jelly or glycerin, whose 
refraction coefficient is far less than that of Canada balsam, a 
diffuse precipitation of silver is sometimes formed on the surface 
of the epithelial cells or in the cell bodies. In each cell, however, 
a clear spherical space, untouched by the precipitate, is present, 
in which a flat nucleus can be observed, when the light is cut 
down. 
