IN SUSCEPTIBLE ANIMALS. 423 



usually inflamed and spotted with haemorrhagic extravasations ; the 

 serous membranes also may be inflamed, and the cavities of the 

 pleurae, pericardium, and peritoneum usually contain more or less 

 fluid. The bacilli are found in the blood vessels throughout the 

 body, and are especially numerous in the interior of the leucocytes. 

 Cornevin and Kitt have shown that the contents of the intestine 

 also contain the bacilli in large numbers, and the disease appears to 

 be propagated among swine principally by the contamination of their 

 food with the alvine discharges of diseased animals. 



Pigeons are very susceptible to the pathogenic action of this ba- 

 cillus, and usually die within three or four days after inoculation 

 with a pure culture. Rabbits are not so susceptible, although a 

 certain proportion die from general infection after being inoculated 

 in the ear. The first effect of such an inoculation is to produce an 

 erysipelatous inflammation. When the animal recovers it is subse- 

 quently immune. 



White mice and house mice are extremely susceptible, but field 



FIG. 139. Section of diaphragm of a mouse dead from mouse septicaemia, showing bacilli in 

 a capillary blood vessel. (Baumgarten.) 



mice are immune. This remarkable fact was first ascertained by 

 Koch by experiments with his bacillus of mouse septicaemia. House 

 mice which have been inoculated with a minute quantity of a pure 

 culture of the rothlauf , or mouse septicaemia, bacillus, die in from 

 forty to sixty hours. The animal is usually found dead in a sitting 

 position, with its back strongly curved, and for many hours before 

 death it remains quietly sitting in the same position ; the eyes are 

 glued together by a sticky secretion from the conjunctival mucous 

 membrane. At the autopsy the spleen is found to be very much en- 

 larged, and there may be a slight amount of oedema at the point of 

 inoculation. 



