STRUCTURE OF THE MAMMALIAN GASTRIC GLANDS. 367 



a piece of mucous membrane be snipped off, and as thin a 

 section as possible prepared with a razor moistened with 

 aqueous humour, and mounted under a cover in a drop of the 

 same fluid, it may be observed, under a low power and small 

 diaphragm, that the mucous membrane is divided into a 

 superficial transparent zone and a deeper more opaque zone 



(%• 1). 



Under a high power (Zeiss, apo. 2 mm. and 8 oc.) the 

 opacity of the deeper zone is seen to be due to the presence 

 of numerous large, coarse granules of zymogen. These 

 granules are entirely absent from the superficial zone, although 

 many minute fat globules may be seen in both kinds of cells. 



The superficial granule-free zone includes not only the pits, 

 but a large portion of the glands themselves; and it may be 

 inferred that the chief cells of the neck of the gland do not 

 contain zymogen in the form of granules. 



This peculiarity of the distribution of zymogen granules in 

 the mucosa did not escape the notice of Langley and Sewall,^ 

 as their figure (14) of the neck of the gland of the cat clearly 

 indicates. They, however, attributed the absence of granules 

 from the neck of the gland to the comparatively infrequent 

 occurrence of chief cells here. 



It will be seen from Avhat follows that the absence of the 

 granules from tlie gland neck is rather to be ascribed to the 

 fact that the chief cells are difi'erent from those of the body 

 of the gland, and are engaged in the secretion of a quite 

 different product. In order that the differences between the 

 two kinds of chief cells may be clearly defined, it will be 

 necessary to describe accurately the ordinary chief cell of the 

 body of the gland. 



In sections from the greater curvature of the stomach of a 

 cat that has fasted one to three days, the chief cells of the 

 body of the gland present the appearance indicated in fig. 2. 

 They are pyramidal or wedge-shaped, and so appear cubical or 

 triangular, according to the direction in which they are cut. 

 Tlie contents of the cell exhibit an exceedingly regular network 

 ' ' Jourual of Physiology,' vol. ii. 



