1889-90.] MORPHOLOGY AND PHYSIOLOGY OF THE CELL. 247 



CONTRIBUTIONS TO THE MORPHOLOGY AND PHYSIO- 

 LOGY OF THE CELL. 



By a. B. Macallum, B.A., M.B., Ph.D., 



Lecturer in Physiology, University of Toronto. 



(Read 15th November, iSgo.) 



In the interior of the epithelial cells of the alimentary canal, and in 

 the glandular cells of the pancreas in ami)hibia, are usually found struc- 

 tures which are of great interest to both the morphologist and the physio- 

 logist. Typical examples of these occurring in the gastric mucosa of the 

 salamander have been described and illustrated by Lukjanow,* and one 

 has but to glance over the figures he has given in order to gain an idea 

 of the number and variety of these bodies. They are much more abun- 

 dant in the intestinal than in the gastric epithelium of a well-nourished 

 animal, and, so far as my observations go, they present, on the whole, a 

 greater complexity of form than those described by Lukjanow. What is 

 the significance of these bodies? With the exception of some of the 

 intranuclear forms, they can, I believe, be arranged in the three follow- 

 ing divisions : 



1. Parasites. 



2. The remains of broken-down cells and nuclei swallowed by the 



healthy adjoining cells. 



3. Material swallowed by the epithelial cell from the food passing 



over its free surface (in the case of the intestinal epithelium). 



4. Plasmosomata migrated or extruded from the nucleus (only in 



the glandular cells of the pancreas). 



It is, no doubt, impossible, in many cases, to determine to which of 

 these classes this or that particular body belongs since intracellular 

 parasites simulate plasmosomata and kindred structures in some stages 

 of their existence, and I propose, therefore, to treat of the structures in 

 a general way, pointing out, wherever possible, their relationship to one 

 or other of the classes given above excepting, however, those connected 



* Beitrage zur Morphologic der Zelle — Arch, fur Anat. und Phys., Suppl. Bd. zur Phys. Abth., 

 1877, p. 66. 



