lOO 
BULLETIN OF THE BUREAU OF FISHERIES 
Plate XXVII. 
Fig. 5. — A quadrant of a transverse section of the intestine taken from a salmon (no. 117) from 
Ilwaco, Wash. This salmon was in the first stage of the migration fast, hence the relative thickness of 
the different layers is vmdoubtedly somewhat different from the normal. However, it shows the relative 
position of the layers and the relative complexity of folding of the mucous epithelial coat. Camera 
outlines. Magnification, Leitz ocular 2, objective 3 (lower lens removed). 
Fig. 6. — ^A superficial sketch of a single caecum chosen from the longer group at the beginning of 
the pyloric intestine of afeeding salmon from Monterey, Cal. This caecum is 8 by 160 mm. The smaller 
caeca have the same relative outlines as the larger. Magnification, X i . 
Fig. 7. — A transverse section of a normal caecum from salmon no. 22, Monterey, Cal. This section 
shows the relation of the different coats, also is especially good to show tlie enormous extent and com- 
plex outlines of the mucous epithelial coat. The wavy band is the stratum compactum which character- 
izes not only the caeca, but the intestine and the stomach as well. Camera lucida outlines. Magnifica- 
tion, Leitz ocular i, objective 3 (lower lens removed). 
Plate XXVIII. 
Fig. 8 . — A portion of the wall of the caecum of a normal feeding salmon (1911 series, no. ii) from 
Monterey, Cal. The magnification in this figure is chosen to bring out the general histological relation- 
ships of the various parts. When tlie section is at exact right angles, as shown in the folds at the left, it 
presents an almost diagrammatic regularity. The folds to tlie right of the figure are complicated, hence 
many of tlie cells are cut at oblique angles. The muscular walls are relatively thin in this section, a con- 
dition that exists when the caeca are distended with food material. Magnification, Leitz ocular i, 
objective 3. 
Fig. 9. — ^A highly magnified section through tlie wall of a pyloric ciecum taken just at the bottom 
of a deep fold. The legend is sufficient to identify the parts. Particular attention is called to the 
relations of the stratum compactum. This dense connective tissue structure is marked on its external 
surface by a network of strands inclosing the cells of the stratum granulosum. These cells are character- 
ized by the imiform and dense loading with highly refractive granules which usually completely obscure 
the small eccentric nucleus. Camera outlines. Magnification, Leitz ocular i, objective 7. 
Fig. 10. — A portion of the cylindrical epithelium and the substratum of the tunica propria highly 
magnified from a feeding salmon (no. 22) from Monterey, Cal. The figure presents a camera lucida out- 
line of the cells, showing their relative size, structure, the relations of the nuclei, etc. Two goblet cells 
in different stages of maturity are shown. In the tunica propria there is a capillary in which lies the 
cross section of a red-blood corpuscle cut somewhat excentric to the nucleus. Camera lucida outlines. 
Magnification, Leitz ocular 4, objective 1/12. 
Fig. II.— Showing a highly magnified group of columnar epithelial cells from the pyloric caecum of 
a Monterey salmon in the active stage of absorption. The fat vacuoles are relatively large and numerous 
in the outer third of the cells. They are present, but more scattered, in the inner limbs of the cells. 
In preparations made with a positive fat stain applied to fresh material these vacuoles are proven to con- 
tain fat droplets. Magnification, Leitz ocular 4, objective 1/12. 
