POLYSACCHARIDE-SPLITTING ENZYMES 305 



specific polysaccharide and regained their capsule when trans- 

 ferred to a medium free of the enzyme. 



The action of the enzyme against Type III Pneumococcus is 

 shown in the accompanying photomicrographs, a description of 

 which follows : 



1. A stained preparation of the peritoneal exudate of a mouse two 

 hours after the intraperitoneal injection of 0.01 cubic centimeter of a 

 virulent culture of Type III Pneumococcus. The bacteria show well- 

 defined capsules, and no evidence of phagocytosis is seen. Many poly- 

 morphonuclear and a moderate number of mononuclear leucocytes are 

 present. (Gram stain. X 1000.) 



2. A corresponding preparation of the exudate of a mouse two hours 

 after receiving the same amount of culture together with 0.5 cubic centi- 

 meter of a preparation of the specific enzyme. The bacteria are devoid 

 of capsules. Polymorphonuclear leucocytes predominate and phagocyto- 

 sis is evident. (Gram stain. X 1000.) 



3. A stained film of the peritoneal exudate of a mouse four hours 

 after injection with 0.01 cubic centimeter of culture alone. The bac- 

 teria are increased in number, encapsulated, and extracellular. The cel- 

 lular elements are polymorphonuclear and mononuclear leucocytes in 

 about equal numbers. (Gram stain. X 1000.) 



4. A corresponding preparation of the exudate of a mouse four hours 

 after receiving the same amount of culture together with 0.5 cubic centi- 

 meter of a preparation of the specific enzyme. Marked phagocytosis 

 has occurred and only an occasional organism is seen outside the ac- 

 cumulated leucocytes, nearly all of which are of the polymorphonuclear 

 type. (Gram stain. X 1000.) 



PROTECTIVE ACTION OF ENZYME IN MICE 



Avery and Dubos then studied the protective action of the en- 

 zyme in mice against Pneumococcus Type III infection. By vary- 

 ing the amount of enzyme with a constant amount of culture, by 

 keeping constant the dose of enzyme and by decreasing the quan- 

 tity of culture, by giving the enzyme before and simultaneously 

 with the infecting dose of culture, and by administering the en- 

 zyme by a single injection into mice eighteen hours after the onset 

 of infection, the authors demonstrated that under the conditions 



