446 PATHOGENIC MICROORGANISMS 



Passive immunization of animals and human beings with the serum 

 of highly immunized horses has been variously attempted by Shiga/ 

 Kraus/ Gay/ and others. All these observers have reported distinct 

 benefit to the patients and a reduction of the mortality by the use of 

 such sera. Striking and rapid reductions of temperature and rapid con- 

 valescence, after a single injection, have occasionally been observed. 

 The earlier workers were inclined to attribute the beneficial results of 

 these sera entirel}' to their bactericidal value. 



Todd has recently demonstrated that the mixture of such an immune 

 serum with solutions of toxin and exposure of the mixture at 37.5° C. 

 for a half hour would produce almost complete neutralization of the. 

 poison, thus demonstrating that at least a large part of the beneficial 

 action of the immune sera was due to a true antitoxic process. Be- 

 cause of the different varieties of dysentery bacilli, polyvalent serum has 

 been recommended. Prophylactic vaccination of human begins with 

 dead dysentery cultures has, so far, led to no practical result. 



Shiga, Deut. med. Woch., 1901. '' Kraus, loc. cit. 



5 Gay, Penn. Med. Bull., 1902. 



