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BULLETIN OF THE BUREAU OF FISHERIES 
work. This network in certain regions forms strong strands quite to the bases of the 
superficial epithelial cells. The connective tissue is of the compact areolar type, the 
fibers of which run in a general way parallel with the stratum compactum beneath. 
This tissue forms a proper support not only for the epithelial coat, including its glands, 
but also for its blood vessels and nerves. N umerous small arteries and veins are present in 
the thicker portion of the tunica, and branches from these form a capillary network in 
the meshes among the glands, as previously stated. The type of connective tissue cell 
present here calls for no particular comment, yet there are a number of cells of the type 
described below as granule cells present just within the stratum compactum. In the 
normal tissue of the tunica these granule cells are not numerous, though in the degen- 
erated tissue, as will be described in a later report, they become more numerous in this 
region. 
Stratum compactum . — A structure of peculiar type and significance because of the 
fact that it is not uniformly present in the walls of the alimentary canals of vertebrates 
is the stratum compactum of Oppel. In the salmon stomach this tissue forms a well- 
developed sheath. It is not in so compact a mass as in the intestine and in the caeca 
described below. Gulland ® says of Salmo solar, “This layer in whatever plane the stom- 
ach is cut is always found as a compact hyaline band lying rather nearer the muscularis 
mucosae than it does to the fundi of the glands. It is, of course, pierced by blood 
vessels, etc., but I have never seen muscle strands from the muscularis mucosae passing 
through it. It contains no nuclei, and no structure can be made out in it by ordinary 
methods. Nuclei lie upon it, however, and the fibers of the connective tissue on either 
side are directly continuous with it (fig. lo).” This characterization of the Salmo salar 
stratum compactum applies very well to the stratum of the king salmon. In the king 
salmon there is the one thick sheath, very heavy and well marked and of wavy outline. 
This thicker sheath lies toward the inner or epithelial side of the gastric wall. How- 
ever, in transverse sections it is always noted that the main portion of the stratum 
bears a network of strands and fibers of the characteristic staining reactions located 
both on its inner and outer surfaces. The network on the outer surface is of heavier 
strands and is about twice as extensive as that on the inner surface. This network of 
fibers runs in a general circular direction. 
The substance of the stratum compactum takes a Mallory connective tissue stain. 
It is shown by this stain to be a homogeneous, compact, nonfibrous mass, evidently of 
collaginous material. Iron haematoxylin stain also fails to reveal fibrous structure. 
Lying on the surface of the strands one notes here and there connective tissue corpuscles. 
The surface is sharply marked by a substance or structure which takes certain stains 
somewhat more sharply than the central portion of the stratum. Occasional nuclei are 
embedded in this superficial layer. 
In the open meshes of the stratum there are always found a number of cells of the 
type designated in this paper as granule cells. These cells form a part of a special coat, 
the stratum granulosum. (See fig. 3, pi. xxvi.) 
o Paton, D, Noel, op. cit.. p. 14. 
