286 BIOLOGY OF PNEUMOCOCCUS 



material or the soluble specific substance — while in immune serum 

 the A substance brought about a quantitatively greater reduction 

 in opsonic activity than its derivatives, although the authors were 

 not able to demonstrate complete inhibition of phagocytic action 

 by the method of absorption of antibody. The A substance by ab- 

 sorption lowered the mouse-protective titer of Type I antipneumo- 

 coccic rabbit serum to a greater degree than did a similar treat- 

 ment with the deacetylated carbohydrate. Analogous to the acetyl 

 polysaccharide of Goebel and Avery, the A substance, adminis- 

 tered in very small quantities, protected mice against an otherwise 

 fatal dose of Type I Pneumococcus, although doses larger than 

 0.005 milligrams failed to establish protection in the animals. This 

 particular antigenic action of the A substance was impaired by 

 boiling in 0.02N sodium hydroxide, and was destroyed by similar 

 treatment with 0.1N sodium hydroxide. 



Enders and Wu also determined that after the injection of the 

 A substance into mice active immunity arose within three days fol- 

 lowing the injection, reached its height in from six to twenty-five 

 days thereafter, and became retrogressive by the forty-ninth day 

 following vaccination. As might be expected, the injection of the A 

 carbohydrate into immunized mice immediately before giving an 

 infective inoculation abolished the active immunity, while the serum 

 of mice actively immunized with the A substance conferred passive 

 immunity on normal mice. The authors suggested that, since the 

 evidence which had accrued in the course of their study indicated 

 that the A carbohydrate obtained from Type I Pneumococcus and 

 the acetyl polysaccharide of Avery and Goebel represented the 

 same chemical substance, the designation A carbohydrate or A 

 substance be relinquished in favor of the more accurately descrip- 

 tive term, acetyl polysaccharide. 



Although Enders and Wu did not include the cellular carbohy- 

 drate of Wadsworth and Brown in their comparison, taking into 

 consideration their observations together with those of Aver}' and 

 Goebel, there is good reason to believe that some of the prepara- 



