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 2>7- 

 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 



