ae CHIKANOSUKE OGAWA 
led to cutting paraffin sections 10 » thick and staining. It was 
impossible because of the structure of the lung to use frozen 
sections in Amphibia and Reptilia, except the snake. The 
sections in the mammalian lungs required a thickness of 40 yu 
to 50 uw for observation of these fibers, even in this thickness the 
results were satisfactory because of the inherent or natural thin- 
ness of the alveolar walls. Frozen sections were used in these 
thick mammalian specimens. Russakoff states that the elastic 
fibers are also stained by this method, resulting in a confused pic- 
ture. I found that in my case no elastic fibers were stained, and 
in general these are easily distinguished by their morphological 
characteristics. 
1. Reticular fibers in Amphibia, Reptilia, and Aves 
Diemyctylus. Many attempts to get sufficient impregnation 
were made, but the results allow only the following observations. 
The surface view shows fine, somewhat parallel reticular fibers 
around the subepithelial blood-capillaries. The fibers are wavy 
in general, but sometimes are straight. It may be that these 
fibers are rather more characteristic of the capillaries than the 
lung itself. The stroma shows no reticular fibers, at least by 
Bielschowsky’s method. 
Rana nigromaculata, Megalobatrachus japonicus. No results 
were obtained. 
Clemmys japonicus. Fine reticular fibers are seen around the 
blood-capillaries. Also there are extremely fine fibers which 
form anastomosing rings around the muscle fibers and fiber 
bundles. The reticular fibers are not visible in the collagenous 
ground substance. 
Gecko japonicus. The technique proved so effective in this 
animal that a detailed description is possible. Two systems of 
reticular fibers are seen, the ones around the blood-capillaries 
and the others in the subepithelial connective tissue. The fibers 
appear to twine themselves closely around the capillaries and 
are marked by an especial fineness, these pursue a circular course 
and are not wavy (fig. 29). In the space of 10 u there are from 
