368 PROTECTIVE INOCULATIONS. 



Chantemesse and Widal (1888) first showed by experiment thai 

 susceptible animals could be made immune against the pathogenic 

 action of this bacillus by the subcutaneous injection of sterilized cul- 

 tures. Having found that four drops of a bouillon culture, three 

 days old, injected into the peritoneal cavity of white mice caused the 

 death of these animals within thirty-six hours, they proceeded to in- 

 ject small quantities (one-half cubic centimetre) of a culture which 

 had been sterilized by heat, and found that after several such protec- 

 tive inoculations the mice no longer succumbed to infection by an 

 unsterilized culture. 



In experiments made upon rabbits, Bitter (1892) arrived at the 

 conclusion that the immunity which he produced in these animals by 

 the intravenous injection of concentrated sterilized (by filtration) cul- 

 tures was due to the presence of an antitoxin in the blood of the 

 immune animals. Having found that control animals were killed by 

 intravenous injections of one cubic centimetre of his concentrated 

 solution of the products of the typhoid bacillus, he added to twice 

 this amount of the toxic solution a certain quantity (?) of blood 

 serum from an immune rabbit, and injected the mixture into the 

 circulation of rabbits with a negative result. Control experiments 

 in which the toxic solution was mixed with blood serum from non- 

 immune animals showed that this had no antitoxic effect, and the ani- 

 mals died. Bruschettini obtained (1892) similar results in his ex- 

 periments upon rabbits with cultures sterilized by heat (60 C.). He 

 concludes from his experiments that the blood serum of rabbits im- 

 munized in this way not only possesses antitoxic properties, but that 

 it has greater germicidal potency for the typhoid bacillus than the 

 blood of normal rabbits. 



Stern (1892) has made experiments to determine whether the blood 

 of recent convalescents from typhoid has greater germicidal power 

 for the typhoid bacillus than that of other individuals. The result 

 showed that the blood serum from persons who had recently recovered 

 from typhoid fever had no increased germicidal power, but rather 

 showed diminished potency for the destruction of typhoid bacilli. 

 But blood from a man who had suffered an attack seventeen and a 

 half years previously was found to have unusual bactericidal power, 

 although it did not protect white mice from typhoid infection. On 

 the other hand, blood from recent convalescents served to immunize 

 white mice, thus indicating the presence of an antitoxin. This is 

 also shown by the experiments of Chantemesse and Widal (1892), 

 who report their success in immunizing susceptible animals by in- 

 jecting the blood serum of other animals previously made immune by 



