CHEMICAL CONSTITUENTS 265 



Type III Pneumococcus, which they succeeded in coupling with se- 

 rum globulin. Avery and Goebel 45 then reported the important and 

 fundamental observation that this artificial, specific carbohydrate- 

 protein complex was able to immunize rabbits against infection 

 with virulent Type III pneumococci, and that the serum of rabbits 

 thus immunized contained type-specific antibodies which precipi- 

 tated the Type III capsular polysaccharide, agglutinated Type 

 III pneumococci, and specifically protected mice against Type III 

 infection. From the results it would seem that the antipneumo- 

 coccic response produced by an antigen known to contain but a 

 single component of the pneumococcal cell indicates the unity of 

 the antibodies participating in the type-specific reactions of pre- 

 cipitation, agglutination, and protection, and relates the speci- 

 ficity of these antibodies to that of the capsular polysaccharide as 

 the reactive part of the antigenic molecule. 



ISOLATION OF "a SUBSTANCE" 



What appeared to be a new element among the specific polysac- 

 charides was introduced by Enders 358 in 1930. In autolytic prod- 

 ucts of Type I Pneumococcus a substance was found, thought to 

 be other than the soluble specific substance, which reacted spe- 

 cifically with immune serum as determined by the precipitin reac- 

 tion or, in vivo, by the anaphylactic behavior of appropriately 

 sensitized guinea pigs. Enders prepared autolysates by incubating 

 for seventy-two hours the phenolized, centrifuged sediment from 

 twenty-four-hour dextrose broth cultures of Type I pneumococci. 

 He obtained the nucleoprotein by precipitating with dilute acetic 

 acid the solution derived by dissolving pneumococci with bile ac- 

 cording to the method of Avery and Heidelberger, while the spe- 

 cific carbohydrate was prepared from pneumococci grown in dex- 

 trose hormone broth according to the methods described by 

 Heidelberger and his associates. 



Enders prepared a "normal" antipneumococcic serum by inject- 

 ing rabbits intravenously with cultures of Type I Pneumococcus 



