ON THE PHAGOCYTES OF THE ALIMENTARY OCANAL. 485 
of pathogenic organisms artificially introduced into the ali- 
mentary tract, or as to that of fungi normally found in the 
intestinal canal when its walls are in any way wounded (stran- 
gulated hernia, &c). 
I must be allowed here to thank M. Metschnikoff, under 
whose direction these investigations have been carried out at the 
Pasteur Institute in Paris. M. Metschnikoff has not only ex- 
amined most of my slides, but he, with the greatest kindness, 
has placed his vast technical and literary knowledge daily 
at my disposal. To M. Pasteur my best thanks are due for 
kindly allowing me to work during many months in the insti- 
tute which has been raised to him during his lifetime as a 
token of respect by a grateful humanity. 
IDE 
The tonsils and Peyer’s patches of animals are described as 
consisting of reticulated connective tissue and lymphoid 
follicles. Each may be considered as a lymphatic gland 
covered by a mucous membrane, and hollowed out by crypts 
lined by the same mucous membrane. 
The mucous membrane of the inner aspect of the tonsil is 
covered by stratified epithelium. Below that epithelium the 
tissue is formed by reticulated connective tissue and closed 
lymphoid follicles. The cavities of the crypts contain epithelial 
cells which have been shed, leucocytes and micro-organisms. 
The lymphoid follicles are joined together by a reticulated 
tissue containing small round cells. The reticulum as well as 
the spaces contained within its meshes, the size of the cells 
contained in them, may be very variable. The round-cells in 
the meshes of the lymphoid tissue divide, as Drews' has shown, 
by karyokinesis. I have also frequently been able to see these 
figures in my preparations. Stohr? has proved that leucocytes 
always wander to the surface of the tonsil and fall into the 
cavity of the mouth. 
The Peyer’s glands are larger or smaller groups of lymph- 
1 Drews, ‘Arch. f. mikros. Anat.,’ vol. xxiv, 1885. 
2 Stohr, ‘Arch. f. path. An. und Phys.,’ xeviii. 
VOL, XXX, PART 4,—NEW SER. ai 
