CHEMICAL CONSTITUENTS 289 



ton (1934), 416 who reported that a Type I immunizing antigen, 

 when heated at 100° in 0.1N sodium hydroxide lost 50 per cent of 

 its antigenic strength after one hour of heating, and 94 per cent in 

 two hours. With a Type II antigen in 0.5N sodium hydroxide, the 

 immunizing activity remained the same as that of the control after 

 four hours' heating. The same sample of Type I antigen heated in 

 0.1N acetic acid for two hours lost 50 per cent and in 0.1N hydro- 

 chloric acid 87 per cent of its immunizing power. Its precipitating 

 action, however, remained the same. Of the samples of SSS pre- 

 pared by the technique of Avery and Goebel and heated under the 

 same condition, Type I in one test showed destruction of antigen- 

 icity and, in a second, no loss ; with Type II no loss was observed. 

 In a miscellaneous group of pneumococcal fractions with immuniz- 

 ing activity in dilutions of 1 to 50,000,000 to 1 to 2,000,000, and 

 with variation of hydrolyzable sugar from 12 to 0.25 per cent, ab- 

 sorption end-point from 8 to 0.1 per cent, and precipitin titer from 

 1 to 5,000,000 to 1 to 5,000, Felton found that there was no defi- 

 nite correlation between acetyl group content and immunizing ac- 

 tivity. However, acetyl groups were found in the samples studied 

 ranging from 6.4 per cent in one sample which immunized in a dilu- 

 tion of 1 to 5,000,000, to 1.2 per cent in a sample which immunized 

 in the same dilution. Inasmuch as this information was published 

 merely in abstract form without the presentation of any experi- 

 mental data, it is impossible to set a proper value upon its signifi- 

 cance. 



In 1935, Felton, with Kauffmann and Stahl, 430 gave the details 

 of a method that had been employed in their laboratory for five 

 years in the routine preparation of soluble specific substance of 

 pneumococci. It had been planned to eliminate the time-consuming 

 initial evaporation of the broth culture and to minimize any altera- 

 tion of the chemical and antigenic structure of the carbohydrates. 

 Calcium phosphate was employed as a selective adsorbent for sepa- 

 rating the polysaccharide from the culture medium and its con- 

 stituents. 



Felton and his co-workers stated that the product from the first 



