ON THE PHAGOOYTES OF THE ALIMENTARY OANAL. 493 
microphages) are found in the interior of macrophages. These 
cells, after their inclusion in the larger ones, almost always 
show signs of having been partially digested. In the deeper 
strata, in which the macrophages are most numerous, the number 
of intracellular macrophages is often enormous. 
It is interesting to know whether the macrophages are able 
to take healthy leucocytes into their interior or only those 
already weakened by the struggle with the micro-organisms 
they contain. Now, if the leucocytes which are wandering 
about in the patch be carefully examined, after staining with 
alum-carmine, it will be noticed that the protoplasm of some of 
them is of a dirty yellow colour, whilst their nuclei are somewhat 
deformed and contain colouring matters unequally, the whole ceil 
showing an early stage of degeneration. On the other hand, 
some leucocytes contained in macrophages appear to be perfectly 
healthy. The fact that I have been able to see similar macro- 
phages containing leucocytes within their interior in the rabbit’s 
mesenteric glands, and also in the spleen, leads me to conclude 
that macrophages are able to take into their interior and digest 
apparently healthy leucocytes. Nevertheless it is a fact that 
many of the intracellular leucocytes are microphages loaded with 
micro-organisms (see figs. 9, 10, 13, 14, 15); and it is plain that 
the ptomaines and other poisons secreted by these lower forms 
of life must exert a deleterious influence on the cells containing 
them, and so weaken these structures, making them less 
capable of resisting the attacks of the macrophages. I think, 
therefore, that although the macrophages are able to take into 
their interior and destroy leucocytes which are to all appear- 
ances still healthy, yet they show a preference for the cells 
already weakened from some cause or other ; for instance, the 
microphages, the vitality of which has been lowered _by the 
secretions of the microbes contained within their interior. 
The intracellular leucocytes undergo the following re- 
markable changes (alum-carmine and Weigert’s method). The 
nuclei first become oblong, pointed, and irregular in shape 
(see fig. 10a). At the same time the protoplasm of the cell 
stains of a characteristic yellowish-grey colour (see figs. 10, a, 
