ALIMENTARY TRACT OF THE KING SALMON 
93 
lu the young salmon of fingerling size or smaller the extent of epithelium is relatively 
less; therefore the folds are simpler than has been described for the adult above. This 
is shown in a number of colored figures illustrating the process of fat absorption in young 
salmon, presented in a paper to follow. A similar epithelial folding has been described 
for other fishes, i. e., for the herring, Murcena, and the sturgeon.® 
The cells of the epithelial coat are of two types, and these are fairly uniformly dis- 
tributed, i. e., the usual cylindrical cells, and the goblet cells. It is not desired to discuss 
here the question of the origin of goblet cells from the cylindrical cell, though the current 
views are supported by these observations. 
The cylindrical cells are very slender in the adult, though less so in the younger fish, 
i. e., under i year old. Their size in a number of measurements made on paraffin sec- 
tioned material was from 45 to 63 long by 5 to 6 in diameter. They have slender 
oval nuclei located at the basal two-fifths of the cells. The cytoplasm of these cells 
presents no special structural features under ordinary conditions. If rapid absorption 
of fat is taking place it is shown by the special fat staining of fresh material to be present 
in the cylindrical cells. In paraffin preparations the fat is dissolved out and open empt)^ 
spaces will appear in the cytoplasm (fig. 11, pi. xxviii). No granules have been found 
and nothing comparable to the cells of Paneth have appeared in any of the sections. 
The superficial borders of the cylindrical cells have a striated border marked by a 
homogeneous ground substance set with numerous fine striae running vertical to the 
surface of the cell. 
The goblet cells appear at tolerably regular intervals, though they are not numerous 
in the normal material. Their cell bodies seem a trifle larger on the average than the 
cylindrical cells. If the mucous of the goblet cell has not completely formed, then the 
striated border will be continuous over its surface. Many of these cells are present 
with the mucous content just beginning to discharge, in which state they are most prom- 
inent in appearance. The nuclei of the goblet cells lie nearer the bases of the cells than 
in the adjacent cylindrical cells. They also contain a greater amount of chromatin, 
hence stain more deeply with chromatin dyes. 
The cells at the bottoms of the epithelial clefts or folds do not show any structural 
traits different from those on the folds projecting farthest into the lumen. This leads 
to the conclusion that there are no gland vestiges in the caeca of the salmon homologous 
with the glands of Lieberkiihn, such as figured by Brass ® for the human vermiform 
appendix. Neither have any rudiments of these glands of the type described by Kings- 
bury ^ for the small intestine of Necturus been found. 
A certain number of wandering leucocytes are always found in the normal epithelial 
coat. In all the salmon material examined these white corpuscles are very small in size 
and are greatest in number in the basal region of the epithelial coat. They are not reg- 
ularly distributed, but sometimes are present in groups of two or three. Their nuclei 
o Brass, A.: Atlas der GewebebelehredesMenschen, bd. i, 1896, GoUmgen. Reference from Oppel, Mikroskopische Anatomic, 
bd. u. 
& Kingsbury, Benjamin F.: The histological structure of the enteron of Necturus raaculatus. Proceedings American Micro- 
scopical Society, vol. 16, 1894, pp. 19-64. 
60289° — Bull. 32 — 14- 7 
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