430 BACTERIOLOGY. 



quantities ; in the same way that a tolerance was ac- 

 quired by the tissues for the venom of the rattlesnake in 

 the experiments of Sewall, 1 and similar to that following 

 the injection into the tissues of small quantities of 

 hemialbumose, which in large amounts rapidly proves 

 fatal. 



Of utmost importance to these studies of the blood 

 and fluids of the body are the experiments of Behring 

 and Kitasato 2 upon the production of immunity to 

 tetanus. In their studies upon the blood of animals 

 subjected to -these experiments it was found that it was 

 not only possible to render animals immune from this 

 disease, but that the serum of the blood of these irn- 

 munified animals afforded immunity when injected into 

 the peritoneal cavity of other animals that had not been 

 so protected ; and moreover, that this serum possesses 

 curative powers over the disease after it has, in some 

 cases, been in progress for a time. They found, further, 

 that the serum of animals that had been rendered im- 

 mune to tetanus, when brought in contact with the poison 

 of tetanus, completely destroyed its poisonous properties, 

 and that the serum from animals or from human beings 

 that do not possess immunity to this disease 'has no such 

 power. 



The demonstration by Behring and Kitasato of the 

 fact that the serum of an immunified animal can not 

 only confer immunity to another susceptible animal, but, 

 in the case of tetanus, cure the disease after it is already 

 in progress, is one of the most important steps that has 

 been made in the entire field of study. The subsequent 

 application of the principle involved in that observation, 



1 Journal of Physiology, 1887, vol. viii. p. 203. 



2 Behring and Kitasato : Deutsche med. Woch., 1890, Bd. xvi. p. 1113. 



