160 Chapter VI 



representatives of an infinitely small minority of pathogenic bacteria, 

 the majority resembling the anthrax bacillus in the facility with 

 which they can be cultivated in all sorts of nutritive media. 



The spirillum of recurrent fever of man (Spirochaete ohermeyeri) 

 was the first pathogenic microbe found in an infective disease 

 distinctly human. Discovered a third of a century ago, it has passed 

 through the hands of the most skilful bacteriologists, who have tried 

 all possible methods of cultivating it outside the body. Koch him- 

 self tried to solve the problem, but, in spite of his incomparable 

 skill, did not succeed. Later, Sakharoff^, at Tiflis, discovered a 

 spirillum very similar in appearance which produced a fatal septi- 

 caemia in the goose. He, also, tried to cultivate it, but in vain. His 

 successors have not been more fortunate in this respect. Here, then, 



[170] are two micro-organisms, against which natural immunity should be 

 easily obtainable and in a fashion quite other than that against 

 anthrax. Nothing, indeed, is more frequent than examples of very 

 stable natural immunity against the spirilla of Obermeyer and of 

 Sakharoff". As I wished to obtain a clear idea of the mechanism by 

 which the guinea-pig resists injections of the spirillum of goose 



[171] septicaemia {Spirochaete anserina) I made injections of goose's 

 blood, containing a quantity of these organisms, into the peritoneal 

 cavity of guinea-pigs. This injection, as usual, causes the disap- 

 pearance of most of the leucocytes, as the result of a very marked 

 phagolysis. We know that, under these conditions, the damaged 

 leucocytes allow a certain quantity of the bactericidal cytase to 

 escape. In spite of this the spirilla remain intact and exhibit very 

 active movements in the peritoneal exudation. This exudation, after 

 a period of phagolysis, which lasts for two or three hours, begins to 

 be stocked again with leucocytes which come up in increasing 

 numbers, a fact that does not prevent the spirilla moving about with 

 great rapidity. Even seven hours after the injection of goose's blood 

 we still find many extremely active spirilla among a large number of 

 recently migrated leucocytes, some of which even at this stage contain 

 red corpuscles of the blood of the goose. It is not until later that 

 the ingestion of these spirilla by the leucocytes commences, the 

 leucocytes at last damaging and completely destroying them. This 

 act of phagocytosis may be readily observed in hanging drops of the 

 peritoneal exudation of inoculated guinea-pigs. The attention of the 



1 Ann. de VInst. Pasteur, Paris, 1891, t. v, p. 564. 



