338 CHIKANOSUKE OGAWA 
2. Respiratory epithelium in Reptilia 
The method used for the impregnation of reptilian epithelium 
was identical with that for amphibian material. The results, 
however, were somewhat inconsistent. 
According to Elenz, the respiratory epithelium of the tortoise 
and snake consists of two kinds of epithelial cells, namely, small, 
nucleated cells and flat ones, in which he was unable to demon- 
strate any nuclei. If this is the case, the respiratory epithelium 
of Reptilia must be quite different from that of Amphibia. On 
the other hand, such authorities as Schulze and Osawa seem to 
believe that the respiratory epithelium of the two phyla has the 
same construction. 
Comparing the two views, it is seen that, according to Elenz, 
the respiratory epithelium of Reptilia is not essentially differ- 
ent from that of Mammalia, since the respiratory epithelium of 
the latter, which will be described later, is also composed of 
two kinds of cells, one of which is non-nucleated. According 
to other authorities, the respiratory epithelium of Reptilia and 
Mammalia must be different. Some light is thrown on this 
question in the following account. 
Clemmys japonicus (tortoise). Asis well known, the respiratory 
epithelium of this animal consists of small cells and large flat 
ones (fig. 4). The small ones, which are usually deeply stained 
by the silver solution, take a rhomboidal form and contain 
nuclei. They may appear isolated or in groups of two or five 
cells and they are in close connection with the intercapillary 
spaces. The cell borders which are adjacent to the large, flat 
cells, often curve inward slightly. The intercapillary spaces 
are said by Elenz to be very narrow generally and entirely filled 
up by small cells in groups, which sometimes extend over more 
than the intereapillary spaces. I also found that the inter- 
capillary spaces are in general exceedingly narrow; but sometimes 
wide spaces, such as are seen in amphibia, may appear here and 
there. The intercapillary spaces have a round or an elliptic 
form, being sometimes reduced to a mere slit; in rare cases the 
slit becomes so much elongated that the length amounts to more 
