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 means 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- 
