CHICKEN CHOLERA. 183 



of this bacillus. De Schweinitz has isolated from cultures 

 of the bacteria pure toxic substances with which he has been 

 able to produce immunity. By subcutaneous inoculations 

 with these toxins in cows he was able to develop in their 

 blood-serum an antitoxic substance capable of protecting ani- 

 mals from the disease. The serum of infected animals has a 

 remarkable agglutinating power; with a dilution of 1 to 

 10,000, agglutination can be obtained in an hour. 



CHICKEN CHOLERA. 

 Bacillus Cholerse Gallinarum. 



History. This bacillus was observed by Perroncito, in 

 1878, and described by Pasteur. 



The cause of the disease known in fowls as chicken cholera 

 is due to a short, broad bacillus, with rounded ends, occurring 

 singly or united to form filaments. 



This bacillus stains in a peculiar way with the anilin dyes, 

 its two poles being markedly stained, whereas the centre of 

 the bacillus is scarcely stained at all, giving it very much the 

 appearance of a micrococcus, which it was at first believed 

 to be by Pasteur. It does not stain by Gram's method. 



Biology. It produces no spores and is non-motile. It is 

 easily killed by heat and drying. It grows on all ordinary 

 culture-media. On gelatin in two days the cultures appear to 

 the naked eye as small white points ; under the microscope 

 the colonies are granular and concentric. It does not liquefy 

 gelatin. In stab-cultures its growth on this media resembles 

 that of a nail with a flat head, the head of the nail being 

 closer to the surface of the medium than the point. 



Its growth in agar and bouillon offers nothing character- 

 istic. The bacillus is strictly aerobic. 



Pathogenesis. Chickens, geese, pigeons, sparrows, mice, 

 and rabbits are susceptible animals. Guinea-pigs are im- 

 mune. By inoculation the disease produced in susceptible 

 animals is that of a general septicaemia, the bacillus being 

 found in the blood and all the internal organs. 



By feeding the contaminated material to animals the lesions 



