634 THE POPULAR SCIENCE MONTHLY. 



respond with those of G. and F. Klemperer so far as the produc- 

 tion of immunity is concerned, and also gives an account of ex- 

 periments made by Donissen in which the injection of twenty to 

 twenty-five cubic centimetres of blood or expressed tissue juices, 

 filtered through porcelain, from an immune rabbit into an unpro- 

 tected rabbit, subsequently to infection with a bouillon culture of 

 " Diplococcus pneumonia?" prevented the development of fatal 

 septicaemia. Even when the injection was made twelve to fifteen 

 hours after infection, by inhalation, the animal recovered. Em- 

 merich and Mastraum had previously reported similar results in 

 experiments made upon mice with the Bacillus erysipelatos suis 

 (rothlauf bacillus). White mice are very susceptible to the 

 pathogenic action of this bacillus. But mice which, subsequently 

 to infection, received by injection the expressed and filtered tissue 

 juices of an immune rabbit, recovered, while the control animals 

 succumbed. According to Emmerich, the result in these experi- 

 ments was due to a destruction of the pathogenic bacilli in the 

 bodies of the injected animals ; and the statement is made that at 

 the end of eight hours after the injection of the expressed tissue 

 juices all bacilli in the body of the infected animal were dead. 

 The same liquid did not, however, kill the bacilli when added to 

 cultures external to the body of an animal. The inference, there- 

 fore, seems justified that the result depends, not upon a substance 

 present in the expressed juices of an immune animal, but upon a 

 substance formed in the body of the animal into which these 

 juices are injected. We have, however, an example of induced 

 immunity in which the result appears to depend directly upon 

 the destruction of the pathogenic micro-organism in the body of 

 the immune animal. In guinea-pigs, which have an acquired im- 

 munity against Vibrio Metschnikovi, the blood-serum has been 

 proved to possess decided germicidal power for this " vibrio," 

 whereas it multiplies readily in the blood-serum of non-immune 

 guinea-pigs. (Behring and Nissen.) 



The antitoxines thus far referred to are from animals which 

 have an acquired immunity against virulent cultures of well- 

 known pathogenic bacteria. But we have also experimental evi- 

 dence showing the presence of antitoxines in animals immune 

 against rabies and against vaccinia, two infectious diseases in 

 which the specific infectious agent has not been demonstrated. 

 Prof. Tizzoni, and his associate, Dr. Schwarz, have recently 

 (1892) published the results of their experiments relating to the 

 presence of an antitoxine in the blood of rabbits which have an 

 acquired immunity against rabies. And I have shown by experi- 

 ments made during the past two months that the blood of vac- 

 cinated and consequently immune calves contains an antitoxine 

 which neutralizes the specific virulence of vaccine virus, both 



