294 BIOLOGY OF PNEUMOCOCCUS 



cosity, and precipitated more antibody nitrogen from homologous 

 antiserum from both horse and rabbit than did the earlier prod- 

 ucts. When compared with the substance isolated by Sevag, the 

 high nitrogen, low amino nitrogen, and optical rotation indicated 

 to Heidelberger and his associates the presence of a nitrogen-con- 

 taining component not present in their products, but there was at 

 the time no way of determining whether the component was an im- 

 purity or an integral part of the polysaccharide as it exists in the 

 organism. 



The study of Heidelberger, Kendall, and Scherp also revealed 

 that, contrary to earlier opinion, the specific polysaccharides are 

 not thermostable. On heating preparations from pneumococci of 

 Types II and III there was an accompanying and marked drop in 

 viscosity without any change in reactivity with homologous anti- 

 serum. There was a decrease in precipitating power in the case of 

 Type I polysaccharide owing to a partial removal of acetyl. The 

 authors suggested that unheated preparations have the largest 

 particle size or longest chain, and that heating results in a degra- 

 dation of the molecule to smaller units. 



In the same communication the authors reported the actual iso- 

 lation of the methyl glucoside of galacturonic methyl ester from 

 the products of hydrolysis of the Type I polysaccharide by methyl 

 alcoholic hydrochloric acid. 



From the properties of the new preparations, Heidelberger, Ken- 

 dall, and Scherp believed that while the products might be arti- 

 facts just as were the older ones, they were certainly a step closer 

 to the native substances themselves and designated the substances 

 as specific polysaccharides of Types I, II, and III Pneumococcus 

 with the abbreviations SI, SII, and SIII.* 



* For the purpose of obtaining a maximal yield of pneumococci with a high 

 polysaccharide content, O'Meara and Browniosi devised a medium consisting of 

 peptone, glucose, sodium chloride and sodium bicarbonate, potassium phosphate, 

 and thioglycollic acid in water. In this medium, Type I Pneumococcus grows 

 rapidly and abundantly. The organisms are found to be rich in capsular poly- 

 saccharide, whereas the medium contains a minimal amount of free polysac- 



