288 BACTERIA IN INFECTIOUS DISEASES. 



result in six out of seven cases. The period of 

 incubation was from fifteen to sixty hours, after 

 which rigors, followed by fever, occurred ; and the 

 typical erysipelatous rash developed itself, and 

 ran the usual course. 



CHOLERA OF FOWLS, cholera des ponies. Pas- 

 teur has furnished satisfactory experimental evi- 

 dence that this infectious disease of the domestic 

 fowl is due to a micrococcus, which he has culti- 

 vated for successive generations in bouillon made 

 from the flesh of a chicken ; but which does not 

 multiply in yeast-water, a culture-medium well 

 suited for the development of many species of 

 bacteria. 



Inoculation of healthy fowls with a pure culture 

 of this micrococcus gives rise to the disease ; but 

 not invariably, as a marked difference in suscepti- 

 bility exists in different individuals. Out of eighty 

 fowls inoculated by Salmon, six recovered, twenty- 

 five were not visibly affected, and forty-nine died. 



One attack protects from subsequent attacks, 

 and protective inoculations may be practised with 

 "attenuated virus " prepared by Pasteur's method, 

 long exposure to oxygen. 



The most potent virus is that obtained from a 

 fowl which dies from a chronic form of the disease. 

 In these cases, "the fowl, after having been very 

 sick, grows thinner and thinner, and resists death 

 for several weeks or months. When it perishes, 

 which occurs shortly after the parasite, located 



