4.96 ARMAND RUFFER. 
13, a). Sometimes part of a bacillus is stained with 
carmiue, the other part taking up gentian-violet, and a bacillus 
may be thus formed of little points staining red and blue 
alternately. 
In a still more advanced stage the micro-organisms do not 
retain either carmine or gentian-violet, and appear as little 
rods or dots, which are extremely pale, and look like the 
shadows of microbes. The rods then breaking up, finally become 
granular, irregular in shape, and refract light somewhat more 
strongly. That is the last stage of the intracellular destruc- 
tion of micro-organisms, , 
If the reader will turn to the descriptionsthat M. Metschnikoff 
has given of the intracellular destruction of micro-organisms 
in pathological conditions, he will see how closely the physio- 
logical processes as seen in the Peyer’s patch resembles the 
pathological one; how, in fact, both are one and the same 
process. 
A few words may now be said concerning the phagocytic pro- 
cesses in the dog’s and guinea-pig’s Peyer’s patches. Macro- 
phages are always present in these as in the rabbit’s lymphoid 
organs, but they are rather scarce compared with the numbers 
found in the latter. Micro-organisms undergoing the process 
of intracellular digestion are found in them also, but in lesser 
numbers than in the last-named animal. Moreover, it is a 
peculiar fact that, whereas the microbes in the rabbit’s tissues 
stain readily with Gram’s method, this is not the case with 
those found in the dog’s or guinea-pig’s cells. T'o demonstrate 
their presence in these animals, various reagents have to be 
used (e.g. Loffler’s blue, fuchsine, methyl-violet, &c.). Even 
then, however, they retain the colouring matter badly, and are 
always pale, and almost colourless. It is probable, that, if 
micro-organisms appear to be less numerous in the dog’s and 
guinea-pig’s Peyer’s patches, this is merely due to our methods 
for staining intracellular micro-organisms being as yet very 
imperfect ; for, although few healthy microbes appear to be 
present, a number of degenerated ones were seen, more espe- 
cially in the guinea-pig’s macrophages. In the macrophages 
