Passive Acquired Immunity 105 



ring andKitasato* found that the blood-serums of animals immun- 

 ized against diphtheria and tetanus, when mixed with cultures of 

 these respective bacilU, neutralized their power to produce disease. 

 Kitasatof found that if mice were inoculated with tetanus bacilli, 

 they could be saved from the fatal infection by the intra-abdominal 

 injection of some blood-serum from a mouse immunized against 

 tetanus, even after symptoms of the disease had appeared. Ehrlicht 

 showed that the blood-serums of animals immunized against abrin 

 and ricin could save other animals from the fatal effects of these 

 respective toxalbumins; Phisalix and Bertrand,§ and, later, Cal- 

 mette|| found the' blood-serum of animals, immunized against the 

 venoms of serpents, similarly possessed the power of neutralizing 

 the poisonous effects of the venoms. Kossel** found that the blood- 

 serum of animals, immunized against the poisonous blood-serum of 

 eels, contained a body which destroyed or neutralized the effects 

 of the eels' serum. 



Thus, it is shown that in each case in which defensive reactions 

 are stimulated in experiment animals, the reactions are accompanied 

 by the appearance in the blood-serum of those animals of factors 

 that can be utihzed to defend other animals in whose bodies no 

 similar reactions have taken place. 



Passive immunity may also be brought about in a few cases 

 by the injection into the intoxicated animal of substances, other 

 than immunity products, that have a specific affinity for the poison. 

 Thus Wassermann and Takakift 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. Wasser- 

 mann also found that the same effects could be produced in the 

 bodies of animals, and that when the crushed spinal cord was in- 

 jected into an animal a few hour previously, or a few hours after 

 a fatal dose of tetanus toxin, enough of the combining elements re- 

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

 central nervous system of the intoxicated animal. MyersJJ 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 accomplished 

 or initiated by factors prepared experimentally, and forced upon 

 the animal in whose body their activities are manifested. 



* "Deutsche med. Woch.," 1890, No. 49. 



.t "Zeitschrift fiir Hygiene," 1892, xii, p. 256. 



X "Deutsche med. Wochenschrift," 1891, Nos. 32 and 44. 



§"Compte rendu Acad, des Sciences de Paris," cxvra, p. 556. 



II" Ann. de I'Inst. Pasteur," 1894, vill, p. 275. 

 ** "BerKner klin. Woch.," r898, p. 152. 

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

 It "Lancet," July 2, 1898. 



