The Antitoxins 135 



Different standards for measuring the strength of the tetanus 

 toxin and different definitions of the unit of measurement are given 

 in different countries, so that great confusion and dissatisfaction 

 were experienced until a special committee of the Society of Ameri- 

 can Bacteriologists met in New York, Dec. 27 and 28, 1906, and in 

 collaboration with the United States Pubhc Health and Marine 

 Hospital Service, Hygiene Laboratory, formulated a standard 

 unit which has become the legal unit of measurement for the United 

 States. It is thus defined: 



"The immunity unit for measuring the strength of tetanus 

 antitoxin shall be ten times the least quantity of antitetanic serum 

 necessary to save the life of a 350-gram guinea-pig for ninety-six 

 hours against the official test dose of a standard toxin furnished by 

 the Hygienic Laboratory of the Public Health and Marine Hospital 

 Service." The unit is thus officially defined, Oct. 25, 1907, in 

 Treasury Circular No. 61. 



Testing tetanus antitoxic serums immediately became a matter 

 of great simpHcity. The governmental laboratory furnishes the 

 "test toxin" whose strength is guaranteed, and what follows is a 

 simple matter of dilution, admixture with the serum to be tested, 

 and the injection of animals that are carefully observed for a few 

 days. 



The entire subject historical, theoretical, and practical, is treated 

 in Bulletin No. 43, 1908, of the Hygienic Laboratory upon "The 

 Standardization of Tetanus Antitoxin," by Rosenau and Anderson. 



Antivenene or Antivenomous Senun.- — This was discovered 

 by PhisaUx and Bertrand* and made practical for therapeutic 

 purposes by Calmette.f Calmette found that cobra venom con- 

 tained two principles, one of which, labile in nature and readily 

 destroyed by heat, was destructive in action upon the tissues with 

 which it came into direct contact; the other, stable in nature, was 

 death-deaUng through its action upon the respiratory centers. By 

 heating the venoms and thus destroying the irritative principle, 

 he was able to immunize animals against the other, which he looked 

 upon as the important element of the venom. The immunized 

 animals furnished an anti-serum, which entirely annulled the effect 

 of the toxin (modified venom) used in treating them. This serum 

 was found to protect rabbits and other animals against both modi- 

 fied and unmodified cobra venom, and was used successfully in 

 the treatment of a number of human beings who had been bitten 

 by cobras. Calmette, however, erroneously concluded that be- 

 cause in most venoms studied he was able to find a larger or smaller 

 proportion of the respiratory poison, it constituted the essential 

 element of the venom to be antagonized. Arguing from this stand- 



* ".Compt. rendu de I'Acad. des Sciences de Paris," Feb. 5, 1894, cxvni, p. 

 3S6. 



t "Compt. rendu de la Soc. de Biol, de Paris," Feb. 10, 1894, 10 Series, i, 

 p. 120. 



