Acquired immunity against micro-organisms 283 



chemiotaxis on the part of the leucocytes, the above cited observers 

 performed the following experiment. They injected into the vein of [297] 

 a rabbit, already affected with a generalised infection by the cocco- 

 bacillus of fowl cholera, an innocuous culture of a saprophytic 

 staphylococcus. Post-mortem examination showed that these cocci 

 were almost entirely ingested by the same phagocytes which refused 

 so energetically to seize the cocco-bacilli. This experiment, analogous 

 to that of Bordet on streptococcus and Proteus, compels us to reject 

 Werigo's conclusions as to the absence of negative chemiotaxis in the 

 phagocytes of the higher animals. I ought to add that the work of 

 Zilberberg and Zeliony was in part executed in my laboratory so that 

 I was able to convince myself by ocular demonstration of the com- 

 plete accuracy of their statements. 



Independently of these observers and even before their work ap- 

 peared, Th. Tchistovitch 1 published an interesting study on the same 

 question. He injected very virulent streptococci into the ear vein of 

 rabbits. These micro-organisms set up a generalised and fatal infec- 

 tion in which phagocytosis was completely absent or nearly so. Here 

 again was manifested a negative chemiotaxis of the phagocytes, which, 

 henceforth, could no longer be questioned. 



In certain infective diseases terminating fatally a very marked 

 phagocytosis is observed even in susceptible animals. The most 

 typical example of this is furnished by swine erysipelas and mouse 

 septicaemia. We know from the researches of Koch 2 , followed by 

 those of Loeffler 3 , Schiitz 4 and others, that in animals which have 

 died from these two diseases the leucocytes are gorged with small 

 specific bacilli. A method of vaccinating animals against the micro- 

 organism of swine erysipelas was worked out by Pasteur and 

 Thuillier 5 and was afterwards studied by many observers. Thanks to 

 this method it has been possible to demonstrate the phenomena which 

 may be observed in vaccinated animals (especially rabbits). Here 

 also a phagocytosis takes place, even more rapid and more complete 

 than in susceptible animals. What is more important, the intra- 

 cellular digestion of the ingested bacilli is followed by the total t 21 



1 Ann. de VInst. Pasteur, Paris, 1900, t. xiv, p. 802. 



2 "Untersuchungen iiber die Aetiologie der Wundiiifectionskrankheiten," Leipzig, 

 1878. [Translated into English in the New Sydenham Society's Series, London, 

 IbSO, Vol. LXXXVIII, under the title "On Traumatic Infective Diseases."] 



3 Arb. a. d. K. Gsndhtsamt., Berlin, 1885, Bd. i, S. 46. 



4 Arb. a. d. K. Gsndhtsamt., Berlin, 1885, Bd. I, S. 57. 



6 Compt. rend. Acad. d. sc., Paris, 1883, t. xcvn, p. 1163. 



