56-± EXPERIMENTAL RESEARCHES WITH CHICKEN-CHOLERA MICROBES, 



first instance only a minute fraction of wild birds may be carried 

 off by the disease — an occurrence which in itself would be of little 

 importance — these few birds, travelling as they may, perhaps, 

 after having become infected, may transmit the germs hither and 

 thither, ready to be taken up again by susceptible birds of the same 

 or some other description. 



Experiments on Common Fowls and Pigeons. 

 (a). 



Feeding and Inoculatio7i. 



On page 553 and Table IV. (at the end), I have already recorded 

 certain inoculation-experiments with reference to common fowls 

 and pigeons. This was in association with the experiments on. 

 the behaviour of chicken-cholera bacteria when removed from 

 rabbit to rabbit through twenty generations. 



' Table YII. (at the end), {a, 6, c, d, e), contains an account of 

 the arrangement and the results of other experiments. 



From it will be seen that one fowl (hen) proved insusceptible to 

 taking chicken-cholera by feeding on a small portion of virulent 

 material from a dead rabbit, while after a second feeding on a 

 considerably larger portion it died, unfortunately, soon afterwards, 

 from some cause different from chicken-cholera. (The result of 

 the j^ost-niortem examination is denoted as negative in the table). 

 Another fowl (heavy rooster) was fed three consecutive times on 

 successively larger portions of virulent material (taken from 

 rabbits) without the least harm to its health. Later on it was 

 inoculated with a small quantity of active microbes, but it 

 remained alive. [Necrotised tissue was thrown out where the seat 

 of inoculation was, corresponding to what takes place in fowls 

 which are treated preventively with attenuated virus of chicken- 

 cholera (Pasteur)]. 



The immunity of the rooster, in this instance, was possibly due 

 to the animal having undergone three previous and successive 

 feeding experiments, which might have had a protective influence. 



