260 BIOLOGY OF PNEUMOCOCCUS 



toward the cause of the still existing uncertainty as to whether 

 chitin is a constituent of the bacterial cell wall.* 



In addition to these specific pneumococcal polysaccharides, Hei- 

 delberger, Goebel, and Avery 611 " 2 isolated from the B strain of the 

 Friedlander bacillus a carbohydrate closely resembling that of 

 Type II Pneumococcus, the similarity extending even to precipi- 

 tation with Type II antipneumococcic serum. But, although there 

 was great constancy in the properties of these two substances, the 

 absorption of agglutinins and precipitins was not reciprocal with 

 the two organisms. It was believed that the cross-relationship was 

 due to the occurrence in the specific polysaccharides of both micro- 

 organisms of the same or similar chemical grouping. Other strains 

 of the bacillus showed no such reciprocal relations, nor was there 

 any such relation between the E strains of the Friedlander group 

 and Type I and III pneumococci.f 



Heidelberger, in the review already quoted, argued that if the 

 fact that bacteria possess mutual absorption capacity be accepted 

 as the criterion of their antigenic identity, then the failure of the 

 Friedlander bacilli to exhibit this property might be taken as fur- 

 ther evidence of the lack of identity of the substances involved. The 

 discussion continued: 



However, granted a chemical difference between the two specific sub- 

 stances, it becomes necessary to account for their marked immunological 

 similarity. In the absence of further evidence as to the structural rela- 

 tions of the two polysaccharides it seems reasonable to assume that 

 both contain in a portion of the complex molecule the same or a closely 

 similar configuration of atoms. The essential similarity in molecular 

 grouping would then determine the immunological similarity of the two 

 substances. In the case of Pneumococcus it has been shown that the 

 polysaccharides by themselves are not antigenic, and it is believed that 



* The foregoing paragraphs are based on the discussion in the paper by 

 Heidelberger and Kendall.eir 



t In this connection it may be mentioned that in the next year Julianelle6S4 

 classified, by their serological reactions, strains of Encapsulate pneumoniae 

 (Friedlander's bacillus) into three types, A, B, C, and one group X. 



It may interest the reader to know that in 1935 Yen and KurotchkinissD by 

 means of electrolysis were able to isolate the specific carbohydrate of the Fried- 

 lander bacillus, apparently free from protein and in a highly antigenic state. 



