STRUCTURE OF THE MAMMALIAN GASTRIC GLANDS. 375 



and others entirely devoid of these. Moreover one can 

 readily distinguish the two kinds of cells from one another, 

 even when, as occasionally happens, the fixation of the granules 

 has been imperfect. In such cases the zymogen-holding cell 

 still stains strongly, although diffusely, in gentian violet, whilst 

 in the neck cell only the nucleus stains. 



In sections from the stomach of an animal that has been 

 digesting for several hours and stained in hiematoxylin, the 

 division into two zones may again be observed. In this case 

 the extensive prozymogen-holding outer zone of the chief cells 

 of the body of the gland stains strongly, showing that the 

 distribution of the prozymogen corresponds to that of the 

 zymogen. The protoplasm of the chief cells of the neck of 

 the gland exhibits but little affinity for hteraatoxylin, and it is 

 only by means of the hsematoxyliu-iron reaction that it in 

 possible to demonstrate the presence of any cytoplasmic chro- 

 matin at all in these cells. In sections of alcohol-hardened 

 material, treated with sulphuric acid alcohol for three to six 

 hours in the warm oven, ammonium hydrosulphide or acid 

 ferrocyanide produce a scarcely recognisable reaction in the 

 protoplasmic portions of the neck cells. If, however, the 

 sections be treated with aqueous hsematoxylin, according to 

 the method already outlined, a slight blue colour is obtained, 

 which, however, is not to be compared in intensity with the 

 strong reaction observed in the chief cells at the bottom of 

 the gland. The protoplasm of the cells of the surface, and of 

 the duct of the gland, gives a similar faint reaction for iron. 



The chief cells of the neck of the gland, therefore, lack the 

 two most important features of the chief cells of the body of 

 the gland ; they contain no granular zymogen, and they contain 

 prozymogen in such small amount that they are rather to be 

 compared in this respect with the mucus-secreting cells of the 

 surface and gland duct. It might be urged that these are 

 young or imperfectly differentiated zymogenic cells, which as 

 yet secrete their ferment in such small amount that its ante- 

 cedents do not appear in the form of granules in the cell. It 

 is not at present possible to determine whether or not these 



