BACTERUL ANTIGENS AND SPECIFICITY 363 



specific substance of Type III pneiimococcus. The polysaccharide 

 appears to be a condensate of 2 molecules of aldobionic acid and 1 

 molecule of glucose. 



The Type A substance yields specific immunological reactions 

 with the homologous type immune serum, but does not give cross- 

 reactions with any one of the three type specific pneumococcus 

 immune sera. The failure to react with pneumococcus Type III 

 serum, considering its chemical similarity to Type III polysac- 

 charide, is apparently due to isomeric configuration. 



Goebel and Avery (1927) found that Friedlander 's Type C 

 soluble specific substance is also a nitrogen-free polysaccharide and 

 that it is chemically similar to tlie one obtained from Type B. 

 Two distinct differences were noted; they show no cross-relation- 

 ship immunologically; they differ in their solubility in water and 

 in their behavior during purification. Pure Type B ia difficultly 

 soluble, while the Type C substance is readily soluble in water. 

 The former is readily precipitated by alcohol in tlie presence of 

 hydrochloric acid, whereas the latter precipitates completely only 

 after standing for one hour at 0° C. Avery and Goebel* (1927) 

 think that the immunological dissimilarity observed in these two 

 substances that are physically and chemically so much alike is 

 probably due to "slight differences in the intramolecular link- 

 age of sugar to sugar, or of sugar to sugar acid. ' ' 



Escherichia coli. — Stuart, Baker, Zimmerman, Brown and 

 Stonet (1940) report the literature along with their own experi- 

 mental studies of the relationship of colifonn bacteria. They say 

 that Magheru (1937) found the entire "0" antigen of Escherichia 

 coli is composed of a sugar-lipoid complex and that the complete 

 antigen was not contained in all of the variants. Precipitin studies 

 indicate many serological varieties for Escherichia coli. Torrey 

 (1938) has found a virulence factor associated Avith the SSS ele- 

 ment but not identical with it. 



E. typhosa. — According to Topley et al. (1937) two carbohy- 

 drate-lipid complexes corresponding to the "0" and ''Vi" anti- 

 gens of E. typhosa have been isolated. These two substances 

 differ in their carbohydrate content and in a few other ways. 



♦A.verv and Goebel: J. Exper. Med. 46: 601. 1927. 



tStuart. Baker, Zimmerman, Brown, and Stone: J. Bact. 40: 101. 1940. 



