376 CHIKANOSUKE OGAWA 
Canis (dog). The dog differs from the above-described mam- 
mals in that the fibers form closer nets. 
Homo (man). In man the elastic fibers are about as close as 
in the dog and they are full of coarse fibers. There is no principal 
difference between the arrangment of the elastic fibers in man 
and in the cat, dog, ete. We have detailed descriptions by 
Linser, Miller, and Orsos. Linser states as follows: ‘“Some- 
times the alveoli are surrounded by a broad layer of elastic fibers, 
sometimes only by one or several fine fibers, and sometimes the 
fibrillary ground substance alone exists under the epithelium.” 
According to my findings, there are always thick fibers passing 
through the alveolar walls in addition to the fine fibers. If Lin- 
ser’s statement, that ‘fibrillary ground substance alone exists 
under the epithelium,’ means the absence of elastic fibers in 
the alveolar walls, then our results disagree. Ors0os distinguished 
two systems in the elastic fibers of the alveolar walls, namely, 
the respiratory and the intercapillary, explaining as follows: 
“The former system branches from the elastic fiber rings of the 
alveolar mouths, spreads in the alveolar walls, and consists of 
strong fibers. The latter starts from the longitudinal elastic 
fibers of the larger blood-vessels, especially the arteries, and goes 
to the alveolar wall. Its course is partly along the ramifying 
vessels and partly independent, and forms fine fiber nets close 
to the capillaries. Both systems are different in origin, struc- 
ture, and function.”” My work confirms the branching of fibers 
from the mouths of the alveolar ducts and the blood-vessel walls, 
but I cannot confirm his statement that the fibers from the 
mouths of the alveolar ducts are thick and that the fibers from 
the blood-vessels are fine. Besides it is difficult to distinguish 
two distinct systems, since greater numbers of the alveoli are not 
in contact with larger blood-vessels, so that the elastic fibers 
of these alveoli are branches of the fiber rings of the mouths of 
the alveolar ducts and alveoli. 
B. Elastic fibers of embryonic and new-born mammals. In this 
study the rabbit, dog, and man were observed. Linser believes 
that the elastic fibers in the lung of the human embryo, thereby 
supposing the same condition in other mammals, are in an 
