CHEMICAL CONSTITUENTS 287 



tions of cellular carbohydrates, though presumably in impure 

 form, are practically identical with the A substance and the acetyl 

 polysaccharide. There is, nevertheless, one point of difference for 

 which as yet no explanation has been forthcoming, and that is the 

 presence of sulfur and phosphorus reported by Wadsworth and 

 Brown in their preparations. Heidelberger never found sulfur or 

 phosphorus in the specific polysaccharides of Type I, II, and III 

 pneumococci and since Avery and Goebel have stated that their 

 highly purified preparation contained neither of these elements, it 

 becomes difficult to reconcile these differences. 



The work of Enders and Wu, taken with that of Avery and 

 Goebel, would seem to demonstrate that the A substance and the 

 soluble specific substance approached very closely in antigenic 

 function the hypothetical specific polysaccharide as it exists in the 

 intact pneumococcal cell. There developed in the latter's study one 

 point, however, which raises a doubt as to the exact common iden- 

 tity of the isolated specific carbohydrate and the native capsular 

 polysaccharide of Pneumococcus. The fact that the former, by ab- 

 sorption, failed to remove all the protective antibodies from the 

 homologous immune serum might be taken to mean that in its isola- 

 tion it had suffered the loss of some completing molecular group, 

 or possibly that its full antigenic power is exerted only when it is 

 in combination with some other constituent of the pneumococcal 

 cell. 



Another striking difference between the acetyl and the deacety- 

 lated polysaccharides of Pneumococcus was manifested in the be- 

 havior of these two derivatives toward the blood-group specific 

 substance A. Witebsky, Neter, and Sobotka 1526 in 1935 announced 

 that a relationship between the soluble specific substance of pneu- 

 mococci and the blood-group substance A of man could be demon- 

 strated by the inhibition of sheep-cell hemolysis by a group-specific 

 A-antiserum, although the various types exhibited certain quanti- 

 tative differences. When, however, the deacetylated carbohydrate 

 was used, it failed to react with the group-specific A-antiserum, 



