328 Granule Cells of Paneth in Intestinal Glands of Mammals 



affinity for basic dyes, such as toluidene blue, sometimes as a diffused 

 substance in the base of the cell, generally in the form of basal filaments. 

 The failure of previous observers to find this substance is probably to be 

 explained by the fact that the study of these cells has generally been 

 undertaken in herbivorous animals which like the guinea pig show the 

 effects of an almost continuous secretory activity. Furthermore, this 

 basal substance, whether diffused in the basal cytoplasm or in the form of 

 the so-called basal filaments, gives when treated by Macallum's method 

 a decided reaction for iron. For these reasons it seems certain that we 

 have to do here with a substance exactly comparable to the prozymogen 

 of other zymogenic cells. 



In the opossum the cells of Paneth are found not only in the glands 

 of Lieberkiihn, but also on the surface of the mucous membrane. In- 

 deed, when the small size of the cells in the glands, their large size on 

 the villi, and the generally rudimentary character of the glands in this 

 animal are taken into consideration, it seems probable that the cells are 

 formed in the glands, but only reach physiological maturity after mi- 

 grating to the surface in the way described by Bizzozero. This is of 

 course only true, as far as we know at present, of the opossum, although 

 it is possible that the examination of other polyprotodont marsupials 

 might reveal similar conditions in them. In placentals the cells of 

 Paneth appear to be confined to the bottoms of the glands of Lieberktihn, 

 which thus function as true glands as maintained by Oppel. 



Whether the condition found in the opossum is the primitive condi- 

 tion for mammals or not it is impossible to say, although this view pre- 

 sents many interesting possibilities. Nicolas' observation that they oc- 

 cur as a part of the general intestinal epithelium in a lizard points in 

 this direction. The observations bearing on the occurrence of Paneth 

 cells in lower vertebrates are, however, as yet, too few to enable any 

 opinion to be offered as to their phylogenetic source. 



The distribution of the cells of Paneth in the opossum absolutely ex- 

 cludes the possibility of the cells of Paneth being young mucous cells, 

 and equally opposed to this view are the facts brought out by Nicolas, 

 Holier, and the writer, as to the indications of active secretion in the 

 structure of the cells and as to their response to physiological stimulation. 



The cells of Paneth of the guinea pig respond to physiological stimulus 

 of food by secretion as indicated by changes in the form of the cell and 

 reduction in the number and size of the granules. 



The crescent-shaped granules of Nicolas and others are due to im- 

 perfect fixation and have no previous existence in the cell. 



