1883.] Changes which take place in them during Secretion. 29 



nogen when present in cells in sufficient quantity to be readily 

 observed is present in the form of granules, hence it seems 

 probable that in cells which contain a small amount only of pep- 

 sinogen, the pepsinogen is also present in the form of granules 

 which however are not conspicuous on account of their small size. 



And in fact in most cases, the less pepsinogen a cell contains 

 the smaller are its granules ; this is especially well seen in the 

 gastric glands of lower vertebrates, in some of these moreover the 

 glands near the pyloric region may be semi-transparent and appa- 

 rently homogeneous during life whilst after treatment with osmic 

 acid, granules become obvious, which except as regards size are like 

 the granules, granules which are of the anterior region of the 

 stomach visible in life in the cells. Since the granules are in these 

 cases preserved by osmic acid, their detection is easy. 



It is then probable that pepsinogen when present in a cell is 

 present in the form of granules, and that when pepsinogen is 

 present in small quantity the granules will be too small to be 

 easily seen. Now the semi-transparent chief-cells of the posterior 

 gastric glands of the rabbit do contain pepsinogen, but they con- 

 tain comparatively little ; and the still more transparent pyloric 

 gland-cells also contain pepsinogen but they contain much less 

 than the chief-cells ; hence I conclude that the granules which are 

 fairly well seen in the one, and indistinctly in the other, in fresh 

 teased out specimens, are really pepsinogen granules comparable 

 to those easily seen in the majority of the chief-cells of mammalian 

 gastric glands. 



With regard to the border cells, there is no satisfactory proof 

 that they contain pepsinogen, and the evidence for the presence 

 of granules in these rests simply on the granular appearance of 

 the fresh teased out cells, evidence which I readily admit to be 

 anything but conclusive. 



I may now pass to consider how the statement given above of 

 the changes which take place in the cells during digestion har- 

 monizes with the description given by Heidenhain 1 and others. 



The serous cells, the mucous cells and the chief-cells of mam- 

 malian gastric glands, after treatment with alcohol, are described 

 as being more granular and as staining better, in the active than 

 in the resting state ; that is, during secretion there is an increase 

 of granular substance staining with carmine, and a decrease of 

 substance not staining with carmine. The granular staining 

 substance, Heidenhain considers to be protoplasmic substance ; 

 with this I agree, except that I consider the apparent granules of 

 alcohol specimens to be parts of the cell network indistinctly seen, 

 so that I take the increase of staining substance in the cells 



1 Cf. Handbuch. d. Physiol. (Hermann), Bel. v. 1880. 



