290 BIOLOGY OF PNEUMOCOCCUS 



had shown characters differing from those of the soluble specific 

 substance of Heidelberger and Avery. The new preparation pre- 

 cipitated more protein from a given immune serum ; it consistently 

 removed all the protective antibody from an homologous serum; 

 and it produced immunity in white mice. The authors were not in- 

 clined to grant the validity of Avery and Goebel's explanation that 

 this immunizing property depended upon the presence of the acetyl 

 group in the polysaccharide. They had, it seems, in a comparative 

 test succeeded in actively immunizing white mice not only with 

 their preparations but also with a sample of soluble specific sub- 

 stance prepared by Heidelberger by his original method. Some 

 statement as to the presence or absence of the acetyl group in their 

 and Heidelberger's own preparation would have been helpful in ar- 

 riving at a just appraisal of their contention. 



In the latest paper to come from Felton's laboratory (1936), 

 its authors (Felton and Prescott) 431 present evidence which, in 

 their opinion, challenges the validity of the theory that the specific 

 antigenic properties of pneumococcal polysaccharides are due to 

 the presence of the acetyl group in the molecule. Because of the 

 seeming heterodoxy of the claim, the summary and conclusions are 

 here repeated practically verbatim : 



A method has been indicated by which the linkage between the units 

 in the polysaccharide of Type I pneumococcus are altered with con- 

 current changes in biological activity. This alteration is shown by both 

 the high titer in bisulfite and iodine reactions in the original material 

 and the absence in samples B* and C* of reducing sugars on hydrolysis 

 after destruction of the aldehyde groups in hot NaOH solution. 



* Sample A was a purified preparation consisting of a mixture of seven sam- 

 ples of Type I polysaccharide prepared by different methods both from the 

 supernatant broth (of pneumococcal cultures) and from the bacterial cell 

 ( Pneumococcus ) . 



Sample B was the original A dissolved at pH 7 in a concentration of 1 mg. 

 per cc, and then made alkaline to N/10 concentration with NaOH and heated 

 in an Arnold sterilizer at 100°C. for 30 minutes. To the alkaline solution after 

 cooling were added 2 volumes of a 1 : 1 alcohol-ether mixture. The white precipi- 

 tate which formed was washed thoroughly with alcohol, alcohol-ether, and dried. 



Sample C was made from the foregoing fraction (B) by treating a neutral 

 aqueous solution, containing 1 mg. per cc, with one-tenth of the volume of con- 

 centrated NH 4 OH at 4°C. for 18 hours. The NH 4 OH solution was precipitated 



