284 BIOLOGY OF PNEUMOCOCCUS 



of Schiemann and Caspar and of Wadsworth and Brown. As in the case 

 of these substances, the acetyl polysaccharide is antigenically effective 

 in mice only when administered in extremely minute quantities. Al- 

 though an extensive study of the purpura-producing action of the acetyl 

 polysaccharide has not been made, in several instances purpura has 

 been noted in mice injected with amounts of this substance ranging 

 from 0.4 to 4.0 mg. . . . That the antigenic action of the water-soluble 

 fraction of Perlzweig and his co-workers may have been due to the 

 presence of traces of unhydrolyzed acetyl polysaccharide seems not un- 

 likely from the readiness with which it lost its immunizing capacity 

 when heated in alkaline solution. 



The correspondence of the acetyl polysaccharide to the A sub- 

 stance of Enders and to the cellular carbohydrate of Wadsworth 

 and Brown has already been mentioned. The exact relation of the 

 acetyl polysaccharide to the "non-carbohydrate and probably non- 

 protein" derivative of Pneumococcus described by Felton still re- 

 mains to be determined. 



Avery and Goebel had found, under the conditions of their ex- 

 periment, that the acetylated polysaccharide failed to induce any 

 immune response in rabbits. The serum of the treated animals 

 contained no demonstrable antibodies, and the animals were not 

 protected against subsequent infection with organisms of the ho- 

 mologous type. It was shown, furthermore, that the acetyl poly- 

 saccharide persisted in the circulation of the treated rabbits for 

 considerable periods of time, was slowly excreted by the kidney, 

 and appeared in the urine in its naturally acetylated form. This 

 observation, particularly when compared to the immunizing action 

 of the same substance in mice, has an important bearing on the 

 definition of antigenicity. 



In 1934, Goebel, Babers, and Avery 523 sought a better under- 

 standing of the immunological significance of the acetyl group in 

 these complex pneumococcal polysaccharides. For this purpose the 

 authors synthesized the p-aminophenol (3-glucoside of glucose and 

 its monoacetyl ester and then combined these two glucosides with 

 horse serum globulin by means of the diazo reaction. These syn- 



