AGGRESSINS 45 



thermolabile, which prevents rapid death, the other is thermo- 

 stabile and this is favorable to rapid death. 



Bail assumes that a tuberculous cavity in an animal contains 

 a great amount of the aggressin, which prevents chemotaxis of 

 the poly nuclear leucocytes, but no.t of the mononuclears or 

 lymphocytes. 



In the peritoneal cavity into which tubercle bacilli without 

 aggressins, have been injected, an active phagocytosis at once is 

 begun by the polynuclears, and the injected bacilli are in a great 

 measure destroyed, and those left develop more slowly, producing 

 a tuberculosis in normal course of time. It is possible to im- 

 munize animals against this aggressin producing an anti-ag- 

 gressin, which substance will not only neutralize the aggressin 

 but also stimulate the leucocytes to phagocytosis. 



This aggressin theory has been applied to other infections with 

 like results, notably in pneumococcus, typhoid, dysentery, and 

 plague infection. 



