432 HOPKINS. [Vol. XI. 



the body of the gland are, for the most part, cubical in longi- 

 section of the gland, but for a short distance below the mouth 

 the cells are more nearly cylindrical in outline. In Fig. 24 it 

 will be noticed that the cells lining the mouth of the gland are 

 placed obliquely to its long axis. In all the forms examined 

 this arrangement holds true, only to a more marked degree 

 than there represented. Frequently cells were seen so bent 

 that the angle formed equaled at least a right angle. In all 

 cases the convexity of the cells projected towards the exit of 

 the gland; the attached end of the cells reached a much lower 

 level than the opposite end. 



In the pyloric region the glands are quite widely separated 

 from each other; the lining cells of these are situated at nearly 

 right angles to the long axis of the gland. Towards the pyloric 

 valve the glands become shorter and gradually disappear, or 

 pass into the crypts of the intestine. Cilia were not found in 

 these glands or on the surface epithelium. 



Summary. 



The salient points of this paper may be summarized briefly 

 as follows : 



1 . The gastric glands were first discovered by Sprott Boyd 

 in 1836. Two years later Henle and Purkinje each discovered 

 that the glands were lined with cells. 



2. In 1870 Rollet distinguished in the glands of the stom- 

 ach two kinds of cells, which he termed " delomorphous " and 

 "adelomorphous" cells. Heidenhain, in the same year, noted 

 the same distinction under the names of "principal cells" and 

 "parietal cells." 



3. Phylogenetically, the gastric glands first appear in the 

 Selachians. 



4. The ontogenetic development of the glands indicates that 

 they have developed from simple insinkings of the alimentary 

 epithelium. 



5. The differentiation of parietal cells does not occur in 

 the class fishes, and it is doubtful if it does in the Amphibia. 



6. The centers of multiplication of the enteric epithelial 

 cells appear to be at the fundus of the glands. 



