42 THE GROUSE DISEASE chap. 



to enable us to say that they are two well-defined 

 species. 



Experiments of feeding and air infection : — 



Numerous experiments were made on mice, guinea- 

 pigs, and ammers to see whether, by introducing the 

 bacilli into the digestive organs, infection could be 

 produced. For this purpose broth cultures, the viru- 

 lence of which was proved by subcutaneous inocula- 

 tion, were mixed with the food given to mice and 

 guinea-pigs, but in no single instance was any result 

 produced. In the case of the ammers, several drops 

 of the broth culture were directly dropped into the 

 mouth, the beak being held open, and readily swal- 

 lowed. No result followed. 



From this it follows, then, that by ingestion the 

 microbe does not act, and therefore must be said to be 

 destroyed by the gastric fluid, and does not reach in a 

 living state the small intestine. 



It is otherwise with the respiratory organs, for 

 infection by these has been ascertained in the case of 

 the ammers. Several experiments were made in 

 this respect; in one set a bird was inoculated with 

 virulent culture, and then placed in a cage with two 

 normal birds. The inoculated ammer was found 

 very ill the next day, with the one leg drawn up, 

 feathers ruffled, breathing very rapid, eyes closed. 

 The bird died during the second day ; the other two 



