The Digestive System 163 
and showed cell structure clearly, it was with 
difficulty that the details of the glands could be 
determined. 
A high-power drawing of a portion of one of the 
glands is shown in Figure 38. The large alveolus, 
av, to the left, is from the peripheral region of the 
gland and is surrounded, on its free side, by the 
areolar tissue described above. The inter-alveolar 
spaces, which are somewhat exaggerated in the 
figure, are filled with fibers which are arranged more 
or less in layers and hence appears different from 
the surrounding areolar tissue. The alveoli are 
circular or elongated in section, and have fairly 
wide lumina. They are lined with a single layer 
of columnar or cuboidal cells which are very granu- 
lar, so that their walls are difficult to determine. 
Each cell contains, near its base, a very large, 
usually spherical nucleus. These nuclei stain 
darkly and give the dark appearance to the glands 
as seen under low magnification, especially in 
rather thick sections. 
During feeding the epithelium of this region of 
the tongue consists of fewer layers of cells than 
during hibernation but is otherwise unchanged 
from what is described above. The glands con- 
sist, at least in all of the material examined, of 
much fewer alveoli than are shown in Figure 37. 
One of these glands is shown in Figure 39. 
Although no more care was used in fixation 
than in the corresponding tissue of the hibernating 
