IMMUNITY AND SUSCEPTIBILITY. 103 



pathogenic bacteria are inclosed in small collodion cap- 

 sules and inserted into the abdominal or other cavity or 

 beneath the skin, the contained bacteria are subject to 

 the action of whatever fluids pass by osmosis through the 

 collodion, but are protected from the phagocytes. In 

 these capsules the bacteria usually grow luxuriantly, 

 without infecting the animal. The phagocytists use 

 this to prove that bacteria are not destroyed by the body 

 juices. It may mean, however, that no inflammation of 

 importance being set up and no leukocytes destroyed, the 

 juices do not become germicidal ; or it may simply prove 

 Buchner's observation that the germicidal substances do 

 not dialyze. 



Laschtschenko ' has confirmed Van de Velde's obser- 

 vation that heterogeneous serums dissolve the germicidal 

 substances out of the leukocytes. He prepared an extract 

 of rabbit's leukocytes with which he mixed various 

 serums — from the calf, ox, hog, goat, sheep, horse, and 

 dog — whose bactericidal energies had been destroyed by 

 heating to 55 C. The serums appeared to dissolve the 

 alexins out of the leukocytes, as the mixture became so 

 germicidal that bacteria were quickly killed by ex- 

 posure to them. 



The distribution of the bactericidal substances in the 

 organs and tissues has been investigated by many, among 

 whom may be mentioned Schottelius, Hennsen, Kotlar, 

 Kopp, Wroblewski, Brieger, Kitasato, and Wassermann. 

 The most recent researches are by Livingood and 

 Wauters. 2 Livingood 3 investigated the subject thor- 

 oughly, using portions of the organs themselves, and 

 cooked infusions of them in performing his experiments. 

 He concludes : 1. That there are substances in all the or- 

 gans which exert an inhibitory influence on the growth of 

 bacteria. 2. There are slight but inconsistent differences 

 in the degree of inhibition exerted by the organs upon 



1 Munchener med. Wochenschrift, 1899, No. 15. 



* Archiv. d. mid. Expir. et d'Atiat. Path., T. x., 1898, p. 751. 



* Centralb. f. Bakt. u. Parasitenk., 1898, Bd. xxxiii., p. 980. 



/ 



