78 
BULLETIN OF THE BUREAU OF FISHERIES 
the mucous membrane is quite red in appearance, as though filled with an unusual 
supply of blood. 
When a large mass of food is present in the stomach and that in an advanced stage 
of digestion, then the muscular walls are greatly relaxed, the stomach is more flaccid, 
and its diameter is enormously increased. The mucous coat is then quite free from 
folds and the whole wall is relatively thin and pliable. In this condition the capacity 
of the stomach is at its maximum. In another connection I have called attention to 
the finding of as many as i8 squid besides several small fishes in one such dilated stomach. 
In such an instance the diameter of the stomach is greatly increased, but the length 
remains quite constant. 
COATS OF THE STOMACH WALL. 
The anatomical divisions that constitute the stomach wall are essentially the same 
in the king salmon as for carnivorous fishes in general, the details of the structure of 
the salmon comparing very closely with the carnivorous type. Beginning with the 
lining mucous membrane, one may record in their regular order the following coats: 
I. Mucosa. 
1. Epithelium. 
2. Tunica propria. 
3. Stratum compactum. 
4. Stratum granulosum. 
5. Muscularis mucosa. 
II. Submucosa. 
III. Muscularis. 
1 . Muscularis circularis. 
2 . Muscularis longitudinalis. 
IV. Serosa. 
The stomach of the king salmon is characterized by the extensive differentiations 
of the mucosa, which possesses the five coats as outlined above. The structure is note- 
worthy for three features — first, the great differentiation of the gastric glands in the 
cardiac region ; second, the strong development of the stratum compactum in this species; 
and, third, for the presence of a constant and definite layer of cells of special structure 
to be described more fully later as the stratum granulosum. This type of granule cell 
is present constantly, not only in the stomach but in all divisions of the alimentary 
canal. Its size and evident importance in the salmon physiology amply justify its 
description as a definite coat. 
histology of the gastric mucosa. 
The epithelial coat of the salmon stomach presents a rather thick layer. A section 
through this coat will vary according to the location of the area in the stomach from 
which it is taken. In the cardiac region the coat is thickest, the thickness being due to 
the presence of the gastric glands. In the pyloric division of the stomach the structure 
is simpler, as will be described later. 
