PHAGOCYTOSIS 289 



sufficient to lead to death, and examine the peritoneal exudate just 

 before the lethal outcome, we may observe that leukocytes are gradu- 

 ally disappearing, and that finally but a few will be present and the 

 fluid will be swimming with free micro-organisms. In the same way 

 it is well known that the diminution of leukocytes in the circulating 

 blood or even the failure of these cells to increase in the circulation 

 in the course of such diseases as pneumonia, or general infections 

 with staphylococci or streptococci is seriously prognostic of fatal 

 outcome. The conditions here observed point strongly to the ex- 

 istence of substances of negative chemotactic influence which protect 

 the bacteria, not from phagocytosis itself, but from that necessary 

 forerunner of phagocytosis, the approach of the leukocyte. It is 

 necessary to draw this distinction since these phenomena are not 

 merely, as often believed, "antiopsonic," but in truth largely "anti- 

 chemotactic." It is true that Kanthack, 34 and more especially 

 Werigo, 35 have denied the existence of negatively chemotactic bac- 

 terial products, the latter basing his assertion upon the observation 

 that active phagocytosis occurs in the lungs, liver, and spleen of 

 animals dying of infection with virulent germs. However, the* argu- 

 ments of these authors are not conclusive and the mass of experi- 

 mental and clinical evidence which points to a direct failure of 

 leukocyte accumulation in the presence of virulent bacteria in the 

 animal body would alone suffice to render such conclusions unlikely. 

 Moreover, strong evidence in favor of the existence of negatively 

 chemotactic influences, is brought by the extensive experiments of 

 Bail upon the so-called aggressins, discussed in another place, and 

 such observations as those of Vaillard and Vincent 36 and Vaillard 

 and Rouget, 37 which showed that the injection of a little tetanus 

 toxin together with tetanus spores would prevent the ingestion of the 

 spores by leukocytes, and thereby furnish an opportunity for germi- 

 nation and consequent fatal toxemia. 



Similar observations have been made by Besson 38 in the case of 

 the bacillus of malignant edema by the use of the original technique 

 of Pfeiffer. Capillary tubes containing the toxin remained free of 

 leukocytes after subcutaneous introduction into guinea pigs, while 

 similar tubes containing the culture medium alone, or the bacilli and 

 their spores, attracted leukocytes in considerable numbers. 



It is possible, of course, to interpret such phenomena as due to a 

 failure of positive chemotaxis rather than to an active negative 

 chemotaxis. 



Although the phenomena of chemotaxis are most easily studied 



34 Kanthack. Quoted from Adami, loc. cit. 



35 Werigo. Ann. de I'Inst. Past., Vol. 8, 1894. 



36 Vaillard and Vincent. Ann. de I'Inst. Past., Vol. 5, 1891. 



37 Vaillard and Rouget. Ann. de I'Inst. Past., Vol. 6, 1892. 



38 Besson. Ann. de I'Inst. Past., Vol. 9, 1895. 



