DISEASES OF POULTRY. 237 



sion, in which case there is noticeable hypersemia of 

 the surface of the heart. The lungs are often, though 

 not .generally, engorged with dark blood; they are 

 seldom, if ever, hepatized. 



The blood vessels are sometimes filled with a firm 

 clot, and contain but little liquid ; at other times the 

 blood does not coagulate at all. It seems to be those 

 cases where the duration of the disease has been long- 

 est, in which the blood loses its property of coagu- 

 lation. 



The brain, in the case examined, was either normal 

 or not very perceptibly altered. The muscles at the 



seat of inoculation are 

 generally reddened, though 

 sometimes perfectly normal. 

 Causation. — The cause 

 of fowl' cholera is a minute 

 germ which under the 

 microscope presents either 

 a circular or oval -outline. 

 It is one of the bacteria 

 and has been called by 

 some a micrococcus, and 

 by others a bacillus. It 

 is about one fifty -thou - 

 ** ' sandth of an inch broad 



Fie. 73. — Bacilli of fowl cholera. j i. v - 4.1,- *.: 



^ and two or three times 



as long. It grows best at from 85 degrees to 105 

 degrees F. It has no power of movement, does not 

 form spores, and is easily destroyed by drying, by the 

 ordinary disinfectants, and by a temperature of 132 

 degrees F. for 15 minutes. 



In the experiments of the author it was found that 

 the virus was destroyed by salicylic acid 1 per cent ; 



