Sidney Klein 321 



lumen. Fig. 1 illustrates fairly well the nature and distribution of the 

 three kinds of epithelial cells in the glands and in the villi. The prepara- 

 tion is from material fixed in Bensley's bichromate-sublimate-alcohol 

 fluid and stained with iron haematoxylin followed by mucicarmine. By 

 this me'ans the granules are stained blue-black in the cells of Paneth, 

 red in the goblet cells. Thus a sharp differentiation is obtained between 

 these cells even in the glands of Lieberkiihn where the young cells contain 

 comparatively little of the secretion-antecedent. The Paneth cells on 

 the side of the villus are large and resemble very closely typical goblet 

 cells (fig. 2). The theca is filled with large discrete granules which do 

 not react with mucicarmine but on the contrary stain intensely in iron 

 haematoxylin. These granules also stain strongly in the neutral gentian 

 mixture recommended by Bensley, 02, for staining zymogen granules, 

 the mucous goblet cells remaining colorless. The granules in the Paneth 

 cells occupy the meshes of a network which is formed by the cytoplasm 

 separating the granules. At the proximal end these cells are narrower 

 and contain a nucleus which is somewhat elongated in the direction of 

 the long axis of the cell and often slightly cupped on the side next the 

 theca. The basal protoplasm is small in amount and uniformly more 

 deeply stained than that of neighboring cells, with the exception of the 

 narrow cells which are obviously undergoing degeneration. Tested 

 with Macallum's reagents for the detection of organic iron a positive 

 result is obtained but not enough to be convincing evidence of the presence 

 of prozymogen in the cell. The search for basal filaments also proved 

 without result although the positive outcome of these observations in the 

 guinea-pig, to be described presently, gave ground for the belief that had 

 a more abundant material been available, and had it been possible to 

 examine it in different physiological states, a positive result might have 

 been obtained. 



The glands of Lieberkiihn in the opossum are remarkable for their 

 low grade of development, and, although the three main types of cells 

 are present, the amount of secretion which the Paneth cells and goblet 

 cells contain indicates that they are to be regarded rather as young 

 elements than as cells already functioning as secreting organs. Indeed, 

 in some respects, these glands present but little advance over the epi- 

 thelial buds to be found in the intestinal epithelium of Batrachia, and 

 to this extent realize Bizzozero's idea of a gland of Lieberkiihn which 

 serves merely as a place for the production of new cells which ultimately 

 migrate to the free surface and there reach their full functional develop- 

 ment. Many mitoses are always present in the glands, some in mucin- 



