CHEMICAL CONSTITUENTS 245 



soluble acid, far stronger than the Type II substance, and capable 

 of being thrown out of solution by an excess of strong hydro- 

 chloric acid. This property was of great use, not only in separat- 

 ing the specific substance from accompanying glycogen or eryth- 

 rodextrin, but also in effecting rapid purification without the use 

 of ammonium sulfate and with fewer fractionations by alcohol. 

 Successive lots agreed closely in their physical and chemical prop- 

 erties, indicating a much more definite entity than the Type II 

 product. The Type III soluble specific substance was thus isolated 

 as a nitrogen-free polysaccharide. No further purification could be 

 realized either by precipitation with barium hydroxide in excess, 

 or by adsorption on highly active alumina. The yield of this solu- 

 ble specific substance was greatly increased by adding glucose to 

 the broth. 



In the case of Type I Pneumococcus, the amount of the soluble 

 specific substance present in the culture fluid was relatively smaller 

 than in the case of the Type II and III organisms and therefore 

 more alcohol was required for its precipitation from the culture 

 concentrate. Other modifications were necessitated by the insolu- 

 bility of the substance at its isoelectric point (about pH 4), and 

 advantage could be taken of its ability to form a precipitate with 

 barium hydroxide in excess. The specific substance was reprecipi- 

 tated by alcohol in the presence of hydrochloric acid and dialyzed. 

 Being a weak base, it precipitated as the excess of hydrochloric 

 acid was removed. The Type I soluble specific substance also ap- 

 peared to be a carbohydrate, but differed in the lower percentage 

 of sugar liberated on hydrolysis and, what is more distinctive, in 

 containing nitrogen as an apparently essential component. 



Heidelberger, Goebel, and Avery 611 arranged a comparison of 

 the distinguishing characters of the soluble specific substances of 

 Types I, II, and III, and included that of the Type B Friedlander 

 bacillus (to be mentioned later) in the table which is reproduced on 

 the following page. 



The aldobionic acid, CnHi 9 Oi COOH, isolated from the hydro- 



