ALIMENTARY TRACT OF THE KING SALMON 
89 
The mucous epithelium is constantly marked by the presence of two common types 
of cells in addition to the typical cylindrical epithelium; first, mucous cells, and second, 
wandering cells presumably of the leucocyte type. In a normal epithelium the number 
of mucous cells varies through wide extremes. In certain sections they are relatively 
rare, and there are long stretches of epithelium without a single goblet cell. In other 
material the number of mucous cells is relatively great, and certain studies made on 
fasting salmon strongly support the view that the number of goblet cells is greatly 
increased during the early fasting period when the mucous membrane as a whole is 
just beginning its retrogressive changes. Certainly the number of mucous cells is 
greater if the fasting be somewhat prolonged. The observations on the salmon support 
the current view that cylindrical epithelial cells may be transformed into goblet cells. 
The wandering cells are indicated by the small round nuclei interstitially arranged 
with reference to the normal epithelial cells. The nuclei are found chiefly near the 
basal portion of the epithelial coat, but they may also be found between the outer limbs 
of the cylindrical cells. In the normal digesting fish taken from among those feeding 
naturally on the banks at Monterey there are comparatively few of the wandering 
cells. This observation is of special significance in connection with certain theories 
concerning the part these cells are assumed to take in the process of absorption. Cer- 
tainly in the salmon the small number present is strongly against the theory that fat 
absorption is accomplished by the wandering leucocytes. Indeed no evidence support- 
ing this view of their function has been foimd in connection with numerous fat-absorp- 
tion experiments. 
I have been unable to show any particular differentiation in different limbs of 
the intestine, in so far as the mucous epithehum is concerned. The only differences 
noted are limited to complexity of the folding. In the pyloric intestine where the 
spaces between the caeca are small and limited, the intestinal epithelium has very simple 
folds. In the middle of the straight limb of the intestine these folds are more complex. 
Tunica propria . — The tunica propria of the salmon intestine is defined as the 
connective tissue support extending from the bases of the epithelial cells to the stratum 
compactum. The tissue is composed of white fibrous connective tissue of the areolar 
type, carrying cells and nuclei of the connective tissue varieties. It is a very thin 
layer except in those places where the mucosa is folded into deep ridges. In the latter 
case the tunica propria extends into these ridges, forming a connective tissue founda- 
tion for the support of the epithelial coat. 
The strands of the tunica propria support the blood vessels lying under the epithe- 
lium. These blood vessels consist of relatively small arteries penetrating from the 
muscle coat and forming a rich capillary network under the epithelium proper. 
Stratum compactum . — This peculiar structure which has been described in some 
detail for the stomach is also present throughout the intestine. It forms a thick, heavy 
sheath, lying midway between the epithelium and the circular muscle coat of the intes- 
tine. The stratum compactum is not so complex as in the stomach in that it has a 
thinner mass of strands over the surface of the main sheet. A transverse section of 
the intestinal wall will usually show a heavy wavy line of dense nonfibrous connective 
