212 PROTEIN POISONS 



important facts demonstrated by this investigator: (1) 

 Animals may be sensitized with dead pneumococci or 

 with extracts from the same. The sensitizing dose may be 

 given subcutaneously, intraperitoneally, intravenously, or 

 intrapleurally. In order to induce anaphylactic shock the 

 reinjection must be made intravenously or intracardiacly. 

 In the sensitized animal both dead and living pneumococci 

 are dissolved more rapidly than in normal animals. This 

 explains the slight but definite immunity to virulent cultures 

 manifested by sensitized animals. (2) Fresh pneumococci 

 suspended in salt solution and kept at 37 for forty-eight 

 hours, under ether or over chloroform, undergo autolysis 

 by which a poison is liberated. This poison injected 

 intravenously or intracardiacly in normal animals causes 

 anaphylactic shock. In guinea-pigs this poison induces 

 death by spasm of the bronchioles and consequent arrest 

 of respiration. In dogs it causes marked fall in blood- 

 pressure and delays the coagulation of the blood. This 

 poison is split off from the pneumococcus protein not only 

 in autolysis, but also by normal and immune sera and by 

 leukocytic extracts. (3) The cleavage of pneumococcus 

 cell substance by autolysis or the other agents mentioned, 

 is accomplished by proteolytic ferments, as is shown by 

 increased production of amino bodies as the poison is set 

 free. Finally, the digestive process reaches a point when 

 the poison itself is digested and rendered inert. "The fact 

 that virulent pneumococci have within themselves a proteo- 

 lytic enzyme which splits their protein into a highly toxic 

 substance, is strong indication that certain strains of pneu- 

 mococci may cause infection forthwith without first rendering 

 the host allergic. This is quite in keeping with the fact 

 that in pneumococcus infections an incubation period is 

 not an invariable rule. On the other hand, in certain 

 instances, a previous sensitization before symptoms set 

 in, probably occurs. This might well be the case in lobar 

 pneumonia when the chill occurs a week or ten days after 

 the patient contracted a severe cold or bronchitis. The 

 distribution by lobes in typical cases may be related to 



