SPECIFIC BACTERIAL PRODUCTS 457 



8 to 13 days previously. Rosenau and Anderson found that 

 guinea pigs could be thus sensitized with 0.004 cc. of serum 

 and that the poisonous symptoms could be produced with 0.1 

 cc. injected into the peritoneal cavity of a half-grown guinea 

 pig and that 0.1 cc. of horse serum injected subcutaneously 

 was sufficient to produce serious symptoms. This hypersensi- 

 tization of the animal tissues by a small quantity of the pro- 

 teid substance is of much significance in explaining the serious 

 and often fatal results following later injections of the same 

 substance. 



Complement. In the study of the germicidal action of 

 blood serum it has been found that the forces which are able 

 to hinder the development of bacteria in the blood or to destroy 

 them depend upon the presence of an anti-bacterial substance 

 which Buchner 33 designated alexin and which is made inactive 

 by heating to a temperature of 55 C. This substance was 

 designated "mycosozins" by Hankin and "cytase" by Metch- 

 nikoff. Ehrlich called this substance complement (from the 

 Latin complementum, that which fills up completely). It is 

 defined as that constituent of normal and immune serums 

 which is thermolabile, that is, destroyed by heating to 55 C., 

 and which unites with the immune body or amboceptor to 

 produce lysis. 



The production of antitoxins or antibodies. The facts 

 have been established (1) that certain bacteria (especially 

 those of diphtheria and tetanus) produce during their multi- 

 plication in culture media poisonous substances or toxins and 

 (2) when these toxins are repeatedly injected in non-lethal 

 doses into the animal body the blood serum of the injected 

 animals will contain a substance (antitoxin) that will neu- 

 tralize the action of the toxins. This laid the foundation for 

 the application of serum therapy in a practical way. The 

 necessity of some method by which to standardize the anti- 

 toxin and to determine the dose to be used was apparent. The 

 investigations along this line taken up by Ehrlich have yielded 

 the most satisfactory results and his explanations and con- 

 83 Buchner. Centralbl. f. Bakt, Bd. V (1889) p. 817. 



