n8 Immunity 



animals of factors that can be utilized to defend other ani- 

 mals in whose bodies no similar reactions have been produced. 



Passive immunity may also be brought about in a few 

 cases by the injection into the intoxicated animal of sub- 

 stances, other than immunity products, that have a specific 

 affinity for the poison. Thus Wassermann and Takaki* 

 found that when the crushed spinal cord of a rabbit was 

 mixed in -vitro with tetanus toxin, the poison was quickly 

 absorbed by the nerve-cells, so that the mixture became 

 inert and could be injected into animals without harm. 

 Wassermann also found that the same effects could be pro- 

 duced in the bodies of animals, and that when the crushed 

 spinal cord was injected into an animal twenty-four hours, 

 or a few hours previously, or a few hours after a fatal dose of 

 tetanus toxin, enough of the combining elements remained 

 in the blood to fix the toxin before it anchored itself to the 

 central nervous system of the intoxicated animal. Myersf 

 found that the ground-up tissue of the adrenal bodies was 

 able to fix and thus annul the poisonous effects of cobra 

 venom in vitro. 



In all these cases the neutralizing effects are either accom- 

 plished or initiated by factors prepared experimentally, and 

 forced upon the animal in whose body their activities are 

 manifested. 



SYNOPSIS OF THE EXPERIMENTAL STUDIES OF 

 IMMUNITY. 



Very important contributions were made by Ehrlich,t in 

 his work upon the vegetable toxalbumins, ricin, abrin, and 

 robin. Kossel investigated the reactions produced with 

 toxic eels' blood and found that immunity could be estab- 

 lished against their hemolytic action. Phisalix and Ber- 

 trand|| showed that immunity could also be produced in 

 guinea-pigs against the action of viper venom. 



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 



* "Berliner klin. Wochenschrift," Jan. 3, 1898. 

 t "Lancet," July 2, 1898. 



t "Deutsche med. Woch.," 1891, Nos. 32 and 44. 

 "Berliner klin Wochenschrift," 1898. 



j| Atti d XI Congr. med. internaz. Roma, 1894, u, 200-202. 

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



