VIIL] BACTERIUM. 93 



rabbits, may perhaps be a bacterium identical with the above, 

 but this is not definitely settled. 



(b) Bacterium of Davaine' s septicamia. This is a bacterium 

 which was originally derived by Davaine l from putrid ox- 

 blood in the warm season. Injected into rabbits it produced 

 rapidly fatal septicaemia, of the same nature as in the case 

 just mentioned, the blood teeming with a similar kind of 

 bacterium as in Koch's septicaemia just described. The 

 smallest quantity of the blood is again rapidly fatal in its 

 action. It is distinguished from Koch's septicaemia in the 

 rabbit by this, that Davaine's septicaemia is easily trans- 

 missible to guinea-pigs, but not to birds. 



'o . 



FIG. 39, BLOOD OF RABBIT, DEAD OF DAVAINE'S SEPTICAEMIA. 



Dowdeswell 2 has shown that when such blood is 

 thoroughly sterilised (i.e. when the bacteria are killed), it 

 has no longer any infective power. Davaine had first shown 

 that the blood of rabbits dead of this form of septicaemia 

 bears an enormous amount of dilution without the minutest 

 quantity of it losing its pathogenic properties. Dowdeswell 

 has shown that this is easily explained by the enormous 

 number of bacteria present in every drop of the blood. But 

 it has been shown by Gaffky and Dowdeswell that there is 

 no increase in the virulence of the virus when it is passed 



1 Bull. d. FA cad. de Med. 1872. 



2 Proceedings of the Royal Society, No. 221, 1882. 



