ON THE PHAGOCYTES OF THE ALIMENTARY CANAL. 503 
the animal’s phagocytes may be unable to do their work of de- 
struction properly, and a local or general infection follow. 
The pathology of infectious disorders of the alimentary tract 
must be re-studied from that point of view. The pathologist must 
now see how the micro- and macro-phages react when typhoid, 
tubercle, or other micro-organisms have found their way into 
the intestinal walls. And he must also study the processes 
going on in these structures when the walls of the alimentary 
tract are wounded by pressure from within or from without. 
These and other problems will receive a satisfactory answer 
only if pathological observations in the post-mortem room be 
combined with experimental investigations. 
Conclusions. 
1. The wandering cells of the lymphoid tissues of the ali- 
mentary canal have the power of proceeding to the free surface 
of such tissues and of taking into their interior lower micro- 
organisms and foreign matter (charcoal, &c.). 
2. There are two kinds of wandering cells in the lymphoid 
tissues of the alimentary canal : 
a. Microphages (small mono- or poly-nucleated cells). 
6. Macrophages (large mononucleated cells). 
3. The macrophages are developed from the small mono 
nucleated lymphocytes. 
4, Macrophages are able to swallow microphages (leucocytes) 
and to destroy and digest them. 
5. The micro-organisms are rapidly destroyed in the interior 
of the micro- and macro-phages. 
6. Micro-organisms are never found lying free between the 
cells or in the blood-vessels and lymphatics. 
7. The destruction of micro-organisms taking place in the 
normal lymphoid tissues of the alimentary tract resembles in 
all particulars the destructive process following on the inocu 
lation of pathogenic organisms into resistant animals. 
