388 CHIKANOSUKE OGAWA 
in Schulze, Marchand, Miller, etc., so that I will merely classify 
it as follows: 
1. The so-called alveolar pores are artefacts. 
2. The alveolar pores are not existent in young animals. 
3. The alveolar pores are existent both in young animals and 
in adults. 
In the microscopic investigation of alveolar pores it is only 
necessary to have thick sections in which alveolar walls are 
darkly stained. Thus the sections studied were selected from 
preparations with ordinary stain, with Bielschowsky stain, or 
with silver impregnation. 
As it was referred to in the work of Schulze and Marchand, 
we observed that the intercapillary spaces in the alveolar walls 
of the lungs of the mole and bat lacked membranes. These 
spaces form pores. I agree with Marchand that there are seldom 
membranes in the intercapillary spaces. These membranes, 
when found, are perforated by several pores around which cells 
approximate closely. It was mentioned above that the inter- 
capillary spaces in the alveolar walls in the lung of the young 
mole were not perforated, but were covered with epithelial cells; 
from this I conclude that the frequent alveolar pores in the 
adult mole lung appear as the animal grows. Materials were 
taken, moreover, from the rat, guinea-pig, rabbit, cat, dog, and 
human. ‘They showed in the greater part of the specimens the 
existence of smooth-edged alveolar pores. The number and the 
size of the pores varied even in the same animal, sometimes 
only several pores could be seen in a section and sometimes 
every alveolus showed some pores. Miuiller’s argument that 
the alveolar pores are artefacts seems to stand on an erroneous 
foundation. According to v. Ebner, it is difficult to decide 
whether or not the pores are artefacts. I am able to perceive in 
the surface view of the alveolar walls that there are breaches 
resulting from the treatment in preparation. These pores can 
be distinguished from the true alveolar pores because the latter 
differ markedly in being smooth-edged and round or elliptically 
shaped. By the regularity of shape it is impossible to deem them 
artefacts. In adult animals a few isolated cases showed no 
