162 



Chapter VI 



ingestion of the spirillum. Once inside the phagocyte the spirillum 

 is digested and soon becomes unrecognisable. 



Recently, Sawtchenko 1 took advantage of an epidemic of recurrent 

 fever at Kazan to make similar investigations on the natural im- 

 munity of the guinea-pig against Obermeyer's spirillum. He observed 

 that these organisms, when injected into the peritoneal cavity, 

 remained there, alive, for 24 and even 30 hours, whilst these same 

 spirilla, when kept at 37 C. outside the organism in their natural 

 medium, died at the end of some (4 7) hours. The injection of 

 [172] human serum containing spirilla into the peritoneal cavity of guinea- 

 pigs set up a phagolysis succeeded by a considerable afflux of 

 leucocytes. In spite, however, of the arrival of quite an army of 

 these cells, the spirilla continued to move rapidly ; for a long time 

 they evaded the phagocytes which, however, in the end always 

 ingested them. But it is only the macrophages which fulfil their 

 phagocytic function (Figs. 32 and 33) ; the microphages obstinately 



Fio. 32. Macrophage of guinea- 

 pig filled with spirilla of recur- 

 rent fever (after Sawtchenko). 



Fio. 33. Macrophage of guinea- 

 pig containing three Spirochaete 

 obermeyeri (after Sawtchenko). 



exhibit an absolutely negative chemiotaxis. Now, as the macro- 

 phages do not make their way into the peritoneal cavity until after 

 the microphages have appeared, it is easy to understand that phago- 

 cytosis can only take place at a late period. Sawtchenko came to 

 the conclusion that " in the peritoneal cavity of animals naturally 

 refractory, the spirochaetes perish as the result of a slow phagocytosis 

 and not from the action of the bactericidal substances of the fluids." 



* Arch, russes de path<,l. etc., St P^tersb., 1900, t. ix, p. 578 ; and Sawtchenko et 

 Melkich, Ann. de Flnst. Pasteur, Paris, 1901, t. xv, p. 502. 



