CONTENTS xi 



stituent of the pneumococcal cell. Cause of differences in 

 carbohydrates isolated from Pneumococcus. Relation of 

 the acetyl group to the immunological activity of Pneumo- 

 coccus. Recent methods of preparing capsular polysaccha- 

 ride. Other physicochemical properties of the capsular 

 polysaccharide. Summary. 



IX. SPECIFIC POLYSACCHARIDE-SPLITTING ENZYMES 301 



First isolation of polysaccharide-splitting enzyme: SI II 

 bacillus. Effect of the enzyme on the cell capsule. Pro- 

 tective action of enzyme in mice. Philosophical aspect of 

 the action of the enzyme. Methods of production. Effect 

 of enzyme on infection induced in rabbits. Effect on in- 

 fection induced in monkeys. Isolation and study of other 

 bacteria possessing polysaccharide-splitting enzymes. 

 Differences in susceptibility of polysaccharides to en- 

 zymatic action. Summary. 



X. ANTIGENICITY OF PNEUMOCOCCUS 323 



Antigenic spectrum. First observations of immunity. In- 

 fluence of virulence on immunological response. Dead 

 cultures: heat-killed antigens; other devitalized antigens. 

 Sensitized pneumococci. Filtrates and extracts : culture 

 filtrates and bacterial extracts ; tissue extracts and exu- 

 dates. Toxins and hemotoxins: so-called toxins; hemo- 

 toxins. Methods of administering antigens: intradermal 

 injection; inhalation and intrabronchial insufflation; oral 

 administration. Host response. Antagonistic action of sol- 

 uble specific substance. Summary. 



XI. ANTIBODIES TO PNEUMOCOCCUS 355 



Agglutinins: history; agglutinins in the blood of pneu- 

 monia patients ; agglutination and serological classifica- 

 tion ; agglutinability of pneumococcal variants ; agglu- 

 tinins in the blood of animals ; additional data. Precipi- 

 tins : history ; antiprotein precipitins ; somatic carbohy- 

 drate (C Fraction) ; the mechanism of specific precipita- 

 tion; correlation of precipitins with other antibodies. 

 Complement-fixing antibodies. Bactericidins. Antihemo- 

 toxin. Antitoxin. Heterophile antibodies. Phagocytosis: 

 history; sensitization of pneumococci; normal tropins or 

 opsonins ; antiopsonins ; opsonins in pneumonia ; the 

 mechanism of phagocytosis. Protective antibodies: speci- 

 ficity ; relation to other antibodies ; additional data ; 



