ioo Immunity 



The investigations upon other active bodies were soon 

 begun. In 1893 Hildebrand* studied emulsin and found 

 that it produced a definite reaction with the formation, in 

 animals injected, of an anti-emulsin. v. Dungernf studied 

 proteolytic enzymes of various bacteria, and showed that 

 when gelatin-dissolving enzymes were repeatedly injected 

 into anfhials, definite reactions took place, and in the serum 

 a body appeared that inhibited the action of the ferment in 

 a test-tube. GheorghiewskiJ immunized animals to cul- 

 tures of Bacillus pyocyaneus, and found that the reaction 

 provoked caused the appearance in the serum of some body 

 that prevented the formation of the blue pigment so char- 

 acteristic of the organism. Morgenroth applied the same 

 principle to rennet, finding that it produced definite reac- 

 tions, with the formation of an anti-body inhibiting the 

 coagulation of milk. Bordet and Gengou|| found that the 

 fibrin ferment of the blood of one animal was active in the 

 body of another animal, producing an inhibiting substance 

 by which the coagulation of the blood of- the first animal 

 could be delayed. 



The studies of Kraus** showed a new fact, that when 

 filtered cultures of the cholera spirillum were introduced 

 into animals, the serum of these animals, added to the filtered 

 culture in a test-tube, caused the appearance of a delicate 

 flocculent precipitate. 



Wasserman and Schiitzeff found that when cows' milk 

 was repeatedly injected into rabbits, their serum acquired 

 the property of occasioning a precipitate when added to 

 cows' milk, but not when added to goats' or any other 

 milk. If, however, the rabbit had been repeatedly injected 

 with goats' milk or human milk, its serum would precipitate 

 with those milks respectively, and not with cows' milk. 

 The reaction was thus shown to be specifict 



MeyersJJ found that the repeated intraperitoneal injec- 

 tion of egg-albumen into rabbits caused their serum to give 

 a dense precipitate when added to crystallized egg-albumen. 



* " Virchow's Archives," Bd. cxxxi. 



f " Miinchener med. Woch.," Aug. 15, 1898. 



J " Ann. de 1'Inst. Pasteur," 1899. 



" Centralbl. f. Bakt." etc., 1899, xxvi, p. 349. 



|| "Ann. del'Inst. Pasteur," 1903, xvn, p. 822. 

 ** " Wien. klin. Woch.," 1897. 

 ft " Deutsche med. Woch.," 1900. JJ " Lancet," n, 1900. 





