I 



Immunity against pathogenic micro-organisms 139 



the influence of the phagocytes. It is sufficient to withdraw from 

 a frog, that has been inoculated with anthrax spores some time 

 before and kept at a moderate temperature (15° — 25° C), a little 

 lymph and sow it in any nutrient medium (of those employed in 

 the culture of bacteria), in order to see the spores germinate and 

 produce a whole generation of absolutely normal filamentous bacilli. 

 All these phenomena have been carefully studied by Trapeznikofi"^ 

 in a work executed in my laboratory. It is obvious from his experi- 

 ments that the phagocytes of the frog are quite capable of protecting 

 the organism against the anthrax bacillus by ingesting and digesting 

 the bacilli in the vegetative state and by preventing the germination 

 of the ingested spores. This phagocytic action is very important in 

 presence of the fact that the plasmas of the frog allow the spores to 

 germinate and the bacilli to develop and produce abundant cultures. 



The immunity of frogs against the anthrax bacillus that we have 

 just described and which is guaranteed by the activity of the 

 phagocytes, is constant under the conditions of temperature above 

 mentioned (15° — 25° C), conditions which are sufficient, however, 

 to ensure the death of susceptible cold-blooded animals, such as 

 the cricket or Hippocampus, from anthrax. The edible frog, a 

 species that readily accommodates itself to a temperature of 35° C, [148] 

 resists, even under these conditions, infection by the bacillus, as 

 pointed out by Mesnil in a work already cited when treating of the 

 immunity of fishes. The green frog (Rana esculenta) when kept for 

 a long time at this high temperature, so suitable for the development 

 of the anthrax bacillus, reacts by the same phagocytic mechanism. 

 The leucocytes of the lymph and blood, the cells of the splenic pulp 

 and Kupffer's stellate cells of the liver, seize the introduced bacilli 

 and digest them as in any other case of phagocytosis. The brown 

 frog {Rana temporaria) adapts itself but slightly and with great 

 difficulty to the high temperature and dies v/hether it has been 

 inoculated with anthrax or not. Under these conditions the bacteria 

 develop in the body of the dead or dying frogs, but Mesnil insists 

 on the fact that a true anthrax infection is not produced, as has 

 been maintained by Gibier as the outcome of his researches. 



Dieudonne^, however, has found a method of removing the 

 natural immunity of the frog against the anthrax bacillus, by inocu- 

 lating it with an artificial bacterial race wliich he had adapted to 



^ Ann. de VInst. Pasteur, Paris, 1891, t. v, p. 362. 



'^ Arh. a. d. k. Gsndhtsamte, Berlin, 1894, Bd. ix, S. 497. 



