RESPIRATORY SPACES OF THE LUNGS By a 
The respiratory epithelium of Tropidonotus natrix consists of two 
kinds of cells, namely, small, nucleated ones, which are always grouped 
in the intereapillary spaces, and large, flattened ones, which contain 
no nuclei and connect the islands of small cells. These groups or islands 
of small cells almost never fill up the whole of an intercapillary space, 
so that large cells come to he totally or partly in them also. Here and 
there one perceives an intercapillary space filled up with two groups 
of small cells divided by flattened cells. It is rarer to find spaces 
which contain only large cells. The groups of small cells in the spaces 
often form quite peculiar, irregular figures with very acute angles. In 
rare cases one finds the groups of two neighboring spaces connected 
by small cells, which run over the intervening capillaries. The num- 
ber of cells, of which a group consists, varies between two and thirty. 
Elenz’s pictures show that the intercapillary spaces are filled 
up principally with numerous, small cells. Before giving my 
opinion concerning the arrangement of the epithelial cells, which 
differs from that of Elenz, I will describe the general construction 
of the Elaphe lung. The septa of the lung are fairly prominent, 
the highest ones, having the same length as the diameter of the 
central canal, becoming gradually lower toward the dorsal aspect 
of the lung and decreasing very much in height near the sac-like, 
caudal part, having here an appearance similar to that of the 
lung of the tortoise. Although the intercapillary spaces do not 
have uniform width throughout, they are in general wider than 
the diameter of the capillaries and also by far wider than those 
of the tortoise. As one would naturally expect, the capillary 
network included in one septum is divided into two layers, one 
for each alveolus. The difference between Clemmys and Elaphe 
Fig. 5 Respiratory epithelium. Clemmys japonicus. Silver impregnation 
(nuclei stained). XX 350. 
Fig. 6 Respiratory epithelium. Elaphe quadrivirgata. Silver impregna- 
tion. Surface view. Darkly dotted round areas show intereapillary spaces. 
x 350. 
Fig. 7 Respiratory epithelium. Gecko japonicus. Silver impregnation. 
' Surface view. Capillaries are dotted darkly. X 350. 
Fig. 8 Lung section. Clemmys japonicus. > 1000. 
Fig. 9 Respiratory epithelium (diagram). Amphibia. In cuboidal part of 
the cell body a nucleus is contained. 
Fig. 10 Respiratory epithelium (diagram). Reptilia. The cell body be- 
comes flat, the nucleus still exists. 
Fig. 11 Respiratory epithelium (diagram). Mammalia. The cell body 
entirely flat, nucleus lost. 
