IMMUNITY. 211 



of this so-called immune serum is called the Neisser-Wechs- 

 berg* phenomenon. The theoretical explanation of this phe- 

 nomenon will be discussed below under Ehrlich's side-chain 

 theory. 



Buxtont reports that the immunization of a rabbit with 

 typhoid cultures does not enable this animal to dispose of a 

 sublethal dose of the bacilli any more quickly than the normal 

 rabbit and that such injections do not produce any appreciable 

 increase of resistance to the endotoxin of the typhoid fever 

 bacillus. 



Analogous to the hypersensibility to infection sometimes 

 noted on the injection of animals with repeated doses of bac- 

 teria is the phenomenon of anaphylaxis seen in animals injected 

 with repeated dose of foreign serum. Animals injected with 

 egg albumin or with blood-serum derived from some other 

 species withstand an amount of the albumin at the first injection 

 which kills them on subsequent injection. Rosenau and 

 AndersonJ have found that the reaction of the animals in this 

 case is specific. That is, guinea-pigs sensitized with horse 

 serum are very sensitive to a second injection with horse serum, 

 but very slightly susceptible to injection with the serum from 

 other animals such as rabbit, cat, dog, hog, sheep, chicken or 

 man. Furthermore, a guinea-pig may be rendered sensitive 

 to three different kinds of proteids at once by injecting the pro- 

 teids either all simultaneously or all separately. 



Active and Passive Immunity. — The kind of immunity 

 which results from the injection of substances from immu- 

 nized animals is called "passive immunity." Diphtheria and 

 tetanus antitoxins produce passive immunity. "Active im- 



*Max Neisser and Friedrich Wechsberg. Ueber die Wirkungsart Bacteri- 

 cider Sera. Miinchner Med. Woch. Jahrg. 48, No. 13, p. 697-700. Munch. 

 Apr. 30, 1901. 



^Journ. Med Research, V. XVI., No. is, May, 1907. pp. 251-274. 



tHyg. Lab. Bui. No. 29 and Bui. No. 36. U. S. Public Health and Marine 

 Hosp. Serv. April, 1906 and 1907 resp. Also Journ. Injec. Dis. Vol. IV., 

 1907. pp. 552-557- 



