INFECTIOUS DISEASES. 633 



sato, Tizzoni and Cattani, G. and F. Klemperer, and others, in- 

 cluding my own. 



Ogata and Jasuhara, in a series of experiments made in the 

 Hygienic Institute at Tokio (1890), discovered the important fact 

 that the blood of an animal immune against anthrax contains 

 some substance which neutralizes the toxic products of the 

 anthrax bacillus. When cultures were made in the blood of dogs, 

 frogs, or of white rats, which animals have a natural immunity 

 against anthrax, they were found not to kill mice inoculated with 

 them. Further experiments showed that mice inoculated with 

 virulent anthrax cultures did not succumb to anthrax septicaemia 

 if they received at the same time a subcutaneous injection of a 

 small quantity of the blood of an immune animal. So small a 

 dose as one drop of frog's blood, or one half drop of dog's blood, 

 proved to be sufficient to protect a mouse from the fatal effect 

 of an anthrax inoculation. And the protective inoculation was 

 effective when made as long as seventy-two hours before, or five 

 hours after, infection with an anthrax culture. Further, it was 

 found that mice which had survived anthrax infection as a result 

 of this treatment were immune at a later date (after several 

 weeks) when inoculated with a virulent culture of the anthrax 

 bacillus. Bearing and Kitasato have obtained similar results in 

 their experiments upon tetanus and diphtheria, and have shown 

 that the blood of an immune animal, added to virulent cultures 

 before inoculation into susceptible animals, neutralizes the patho- 

 genic power of these cultures. Tizzoni and Cattani ascribe the 

 protection of animals which have acquired an immunity against 

 tetanus to the presence of an albuminous substance which they 

 call the tetanus antitoxine. This they have isolated from the 

 blood of immune animals ; and have shown by experiment that it 

 neutralizes the potent toxalbumin of tetanus in test-tube cultures 

 as well as in the bodies of infected animals. G. and F. Klemperer 

 have recently (1891) published an important memoir in which 

 they give an account of their researches relating to the question 

 of immunity, etc., in animals subject to the form of septicaemia 

 produced by the Micrococcus pneumonic?, crouposce. They were 

 able to produce immunity in susceptible animals by introducing 

 into their bodies filtered cultures of this micrococcus, and proved 

 by experiment that this immunity had a duration of at least 

 six months. They arrive at the conclusion that the immunity 

 induced by injecting filtered cultures is not directly clue to the 

 toxic substances present in these cultures, but that they cause the 

 production in the tissues of an antitoxine which has the power of 

 neutralizing their pathogenic action. Emmerich, in a commu- 

 nication made at the recent (1891) International Congress for 

 Hygiene and Demography, in London, reports results which cor- 



VOL. XLI. 46 



