1891.] Wandering Cells in Animal Bodies. 523 
himself found. But Fligge, and others, claim that the parasites 
taken up are really only those which have already been killed, or 
at least injured, by chemical substances of the body, and that 
the white blood corpuscles are simply scavengers that pick up 
dead material, as the lymph corpuscles are known ‘to. destroy 
feeble and broken-down red blood corpuscles in the spleen. 
In experimenting with the anthrax bacillus, Baumgarten found 
that after having been injected into pigeons, the bacilli were very 
seldom taken up by leucocytes, but that they seemed to degen- 
erate precisely as they did when left in distilled water. A great 
many objections have been of the nature of a direct contradiction 
of the observations which Metschnikoff claims to have made. 
For instance, it is stated by Koch that anthrax bacilli, though 
taken up in leucocytes, may actually continue to grow there. 
There are a great many bitter opponents of this eating-cell theory, 
and, no doubt, many observations have been made which would 
be very difficult to explain by it. 
It is apparent from what has been said, that in spite of these 
objections, many facts remain, which are of great importance to 
the study of pathology and therapeutics. It will be of value, 
also, to the medical practitioner to keep himself informed on the 
progress of this work at the present day. 
It is often asked by those who are not able to understand the 
true aim of a science, what practical results are obtained by the 
great search for unknown facts that is being made in the so-called 
natural sciences. Without mentioning the discoveries made in 
this way, which have successfully answered many economic ques- 
tions, it is a noticeable fact that all the knowledge developed by 
this phagocyte theory, and the work it has stimulated, sprang, in 
the first place, from Metschnikoff’s purely morphological re- 
searches. 
If the knowledge obtained from the experiments here er 
ated, cannot be directly applied tothe relief of human suffering, it is 
probable that a foundation has been laid, upon which it may be 
possible to build up methods for operation against the common 
enemy. 
