ON THE PHAGOCYTES OF THE ALIMENTARY CANAL. 497 
of the guinea-pig’s small intestine likewise I have also 
frequently seen micro-organisms. These, however, are difficult 
to stain, and only assume a pale red colour even when subjected 
to the action of a strong fuchsine solution. 
It has already been stated that many leucocytes force their 
way through the epithelial layer of the rabbit’s tonsils to the 
free surface of these organs. These mono- and poly-nuclear 
leucocytes resemble, both in shape and function, those coming 
to the epithelial border of the rabbit’s Peyer’s patch. They 
sometimes contain in their interior small masses of carbon and 
other extraneous matter which they have evidently fetched from 
the free surface of the tonsils; for it is impossible to explain, 
by a mere passive process, the penetration of these dead and 
indigestible matters into the interior of the cells. 
The dog’s leucocytes, near the free surface of the tonsils, are 
often quite full of these ‘masses of carbon and extraneous 
substances. The greater amount of foreign matter in the 
leucocytes of the dog’s tonsils may, I think, be accounted for 
in the following manner. In the first place, rabbits breathe 
through the nose only, whereas dogs breathe through the 
mouth also. Hence a larger quantity of inhaled dust must 
pass over the dog’s tonsils, remain fixed there, and ultimately 
be carried away by the animal’s leucocytes. In the second 
place, rabbits feed on clean vegetable food which contains but 
little dust or foreign matter. Dogs, on the other hand, roam- 
ing about the streets, not only poke their noses into most dirty 
places, but have a habit of taking as food all kinds of refuse. 
Some of the dust, coal, &c., covering that filthy food, must 
stick to the mucous surface of the tonsils and become a prey 
of the ubiquitous leucocytes. 
More minute examination of the epithelial layer covering 
the rabbit’s tonsils reveals the presence of other and much 
larger cells. These have a single clear nucleus staining of a 
rose colour with alum-carmine, and contain in their interior 
peculiar and characteristic yellowish-grey round bodies. 
These large cells exactly resemble aud are indeed macro- 
