THE GROUSE DISEASE 



oculation of two control fowls ; both these latter be- 

 came ill on the fifth day with the typical diarrhoea, they 

 were quiet and off their food. No control experiments 

 were made for testing the virulence of the blood and 

 spleen tissue, because I considered this an unnecessary 

 repetition ; the experiments described in the previous 

 chapter were so clear and decisive as to the virulent 

 character of the blood and spleen tissue of a fowl that 

 had died of fowl enteritis, that it did not require any 

 further confirmation. The above eight fowls that 

 were thus subjected to a second inoculation with viru- 

 lent material showed no signs of any illness, they 

 remained lively, fed well, and at no time showed any 

 diarrhoea, and they remained well for weeks after, till 

 they were discarded. It follows from these experiments 

 that fowls that have passed through a first mild attack 

 of the disease are possessed of immunity against a 

 second attack. It was now most important to discover 

 the material that could be relied upon as producing a 

 distinct but transitory attack of fowl enteritis. 



The first experiments were made with broth sub- 

 cultures from a gelatine culture of the heart's blood of 

 the rabbit mentioned in the previous chapter (sub. 8), 

 as having been the only rabbit out of six that had 

 died after inoculation with broth culture. Seeing that 

 rabbits are so little susceptible to this disease, I thought 

 it not improbable that the bacilli taken from the body 



