AGGRESSINS 39 



with a needle moistened with toxin, has induced tetanic symptoms 

 If tetanus toxin of known strength is mixed in a test-tube with 

 fresh brain substance of a guinea pig, the toxin is no longer toxic 

 for guinea pigs. This shows that there is a chemical union of the 

 toxin and the cells of the brain. Cells of other organs have no such 

 effect. This explains specific action of tetanus upon nervous tissue. 



Aggressins. 



If tubercle bacilli are injected into the abdominal cavity of a 

 guinea pig, rapidly fatal tuberculosis is produced. If the exudate 

 produced in the peritoneum, consisting of lymphocytes, is sterilized 

 and injected into another guinea pig, together with some virulent 

 tubercle bacilli, the animal will succumb in twenty-four hours. If 

 the exudate alone is injected no effect will follow; if bacilli alone are 

 injected, a tuberculous peritonitis will be produce in a few weeks. 

 It is the exudate plus bacilli that does the harm. The exudate is, 

 in this instance, the aggressin. Bail, who originated the doctrine of 

 aggressins, believes that a bacteriolysin is produced, which, acting 

 on the bacilli, liberates an endotoxin, which paralyzes the poly- 

 nuclear leucocytes, inhibiting their action as phagocytes. 



By heating the exudate to 60 C. the aggressins are increased in 

 activity, and it has been found that small amounts are relatively 

 stronger than larger ones. 



This phenomenon has been explained by Bail in this way. He 

 assumes that there are two substances in the exudate, one is thermo- 

 labile, which prevents rapid death, the other is thermostabile and 

 this is favorable to rapid death. 



Bail assumes that a tubercular cavity in an animal contains a 

 great amount of the aggressin, which prevents chemotaxis of the 

 ploynuclear leucocytes, but not of the mononuclears or lymphocytes. 



In the peritoneal cavity without aggressins, into which tubercle 

 bacilli have been injected, an active phagocytosis at once is begun 

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



