Specific Substance of Pneumococcus 435 



tungstic acid, mercuric chloride, or neutral lead acetate, gives a 

 faint haze with tannic acid, and is precipitated by basic lead 

 acetate. At a dilution of 1 :1 ,500,000 it still gives the Molisch 

 reaction and yields a precipitate with Type II immune serum. 

 [<x]d is +58.7°; N, 1.2 per cent.; P, trace; S, none; C, 46.2 per 

 cent.; H, 6.1 per cent. Hydrolysis yielded 79 per cent, of re- 

 ducing sugars, of which glucose was identified by the melting 

 point and optical rotation of its phenylosazone. Earlier prepa- 

 rations containing more nitrogen and yielding less reducing 

 sugars on hydrolysis were not specific at as high dilutions. 



While it is not excluded that the non-carbohydrate portion of 

 the preparation is actually the carrier of the specific reaction, it 

 is believed that the evidence points to the identity of the specific 

 soluble substance with the polysaccharide portion, thus linking 

 it with the bacterial gums isolated by others from capsular ma- 

 terial, but never before connected with specificity. 



217 (2177) 



Immunological relationships of cell constituents of pneumococcus. 



By O. T. AVERY and M. HEIDELBERGER. 



[From the Hospital of the Rockefeller Institute for Medical Re- 

 search, New York City.] 



In the preceding communication, it has been pointed out that 

 the so-called soluble specific substance of pneumococcus is non- 

 protein in nature, and in its present state of purification is either 

 itself a polysaccharide, or intimately associated with the carbo- 

 hydrate. Although antigenically this substance appears capable 

 of stimulating little or no antibody response, serologically it is 

 highly reactive and exhibits to an extraordinary degree the reac- 

 tions of type specificity in antibacterial serum of the homologous 

 type of pneumococcus. On the other hand it is possible to 

 recover from the pneumococcus cell another substance which 

 is protein in character and which is distinctive in its serological 

 behavior from the soluble specific substance. From bile solutions 

 of pneumococci dilute acetic acid precipitates a protein fraction. 

 This precipitate is washed in water and redissolved in dilute al- 



