AGGRESSINS. 337 



general tuberculosis and to the death of the animal 

 in the course of a few weeks. If, during the 

 course of the disease, a second injection of a large 

 quantity of the bacillus is made into the peritoneal 

 cavity, or if an injection of tuberculin is given, 

 the animal dies very quickly. This is, of course, 

 nothing more than the well-known hypersuscep- 

 tibility of tuberculous animals to the products of 

 the tubercle bacillus. In addition to this fact, 

 however, a similar result was obtained in another 

 manner. If a large quantity of bacilli is placed 

 in the peritoneal cavity of a healthy guinea-pig, 

 and the exudate is removed after twenty-four hours 

 and freed from leucocytes and bacilli, the aggressin 

 of the bacillus is said to be present in the clear 

 fluid. This is demonstrated by injecting some of 

 the fluid, together with tubercle bacilli, into the 

 peritoneal cavity of another healthy guinea-pig. 

 The rapid death of the animal is the result, 

 whereas the bacilli alone cause death only after a 

 long period, and the cell-free exudate alone is 

 without toxicity. 



A similar condition has been found in experi- 

 mental infections with a number of bacteria 

 (typhoid, cholera, dysentery, plague, chicken cho- 

 lera), the essential fact being the same: that, fol- 

 lowing intraperitoneal or intrapleural inoculation, 

 the resulting exudate, when freed from leukocytes 

 and bacteria, has the power of . intensifying an in- 

 fection by the corresponding organism. 



There seems at present to be no definite knowl- 

 edge concerning the nature of these aggressins, al- 

 though Bail thinks they may resemble true toxins 

 in some respects. Likewise the precise character 



