360 PROTECTIVE INOCULATIONS. 



by additional investigations, the results of which have been reported 

 in numerous published papers. The authors named have ascertained 

 that when kept in a cool place (15 to 25 C.) the blood serum of 

 immune rabbits retains its antitoxic power for several months, and 

 the antitoxin, obtained by precipitation with alcohol, kept in a dry 

 condition for more than ten months, was found to preserve its original 

 activity. 



Having succeeded in their earlier experiments in immunizing rab- 

 bits and dogs, Tizzoni and Cattani (in 1893) proceeded to experiment 

 upon horses, and were equally successful with these animals. As a 

 result of numerous injections with an attenuated virus, continued for 

 a period of ninety-seven days, they established an immunity which 

 was tested by inoculating the animal with ten cubic centimetres of a 

 gelatin culture, of which one two-hundredth part of a drop killed a 

 white mouse. The antitoxic value of the blood serum of this horse 

 was 1 : 5, 000, 000 i.e., one gramme of this serum would immunize five 

 million grammes of mice, or two hundred and fifty thousand mice 

 weighing twenty grammes each. In a later communication (1894) the 

 authors named report that after freely bleeding immunized horses, and 

 allowing them to rest for one or two months, and then again treating 

 them with small doses of tetanus cultures, the blood serum soon be- 

 comes as active as before the bleeding. The greatest antitoxic power 

 was manifested from twenty to twenty-three days after the completion 

 of the protective inoculations, and a serum was obtained possessing a 

 value of 1 : 10,000,000. According to the authors named the precipi- 

 tated (by alcohol) and purified antitoxin from such a serum, judging 

 from their experiments on lower animals, should cure a case of teta- 

 nus in man in the dose of from forty to fifty centigrammes. 



The authors last mentioned have reported (1892) that the young of 

 immune parents have a certain degree of inherited immunity. And 

 the more recent experiments of Ehrlich and Hubener have confirmed 

 this so far as the inheritance of immunity from the mother (in mice) 

 is concerned; but their results did not show any immunity in the 

 young when only the father had been rendered immune ; and the im- 

 munity inherited from the mother only lasted for two or three months 

 after birth. 



TUBERCULOSIS. 



Metchnikoff states that when kept at a temperature of 42 C. for 

 some time the tubercle bacillus undergoes a notable diminution in its 

 pathogenic power, and that when kept at a temperature of 43 to 44 

 C. it after a time only induces a local abscess when injected subcu- 



