314 CHIKANOSUKE OGAWA 
paraffin sections were used. The paraffin sections were not 
affixed, but treated the same as the frozen sections after the 
removal of the paraffin. The sections were cut to the same 
thickness mentioned in the chapter on muscle fibers. 
A. Elastic fibers of adult mammals. Talpa (mole). In the 
mole there are few muscle fibers, these are paralleled by few 
elastic fibers. These fibers form rings which surround the 
mouths of the alveolar ducts. In the rings in some places the 
elastic fibers form a single sheaf, while in others they present a 
much looser appearance. The large mouths of the alveolar 
ducts are sometimes surrounded by rings consisting of several 
sheafs. In the mouth of periphery of the alveolar ducts the 
individual fibers in the rings are finer. The fiber rings send off 
fibers toward the alveolar mouths and the alveolar walls. In 
the first part of the alveolar ducts the branching fibers which 
run along in different directions the alveolar ducts are strong and 
participate in the formation of rings around the alveolar mouths, 
while we have also the fiber rings which confine the mouths alone. 
In parts other than this there are no branching fibers to 
strengthen the alveolar mouth rings which consist of one or 
more fibers. The fiber rings around the alveolar mouths in turn 
send out several fine fibers into the alveolar walls. 
In this animal the intereapillary spaces are alveolar pores, 
thus the elastic fibers run along the capillaries. In their course, 
the fibers do not follow an individual capillary, but pursue as 
straight a path as the capillary area allows, which results in a 
slightly curved line. The fibers going into the alveolar walls 
anastomose with each other. | 
Vesperugo (bat). This animal resembles the mole in that the 
fiber rings are present around the mouth of ducts and alveoli, 
but differs in that the fibers are coarser and usually loosely 
united. As in the mole, there are fiber rings around the mouths 
of the alveolar ducts which also give off branches running along 
alveolar ducts.and supplement the rings around the alveolar 
mouths. 
In the bat, however, this condition is seen throughout the 
alveolar-duct system instead of being merely in the first part 
