312 A MANUAL OF BACTERIOLOGY 



gested, and very soft and friable. Microscopically, the 

 bacillus is found in enormous numbers in the spleen, 

 somewhat less numerously in the blood, and still less so 

 in the liver, kidney, and other organs. 



Swine do not often suffer from this disease, unless fed 

 with the offal of an infected animal, in which case the 

 chief clinical sign is great enlargement about the*throat ; 

 this is almost pathognomonic, while the chains of bacilli 

 tend to be somewhat longer than in other animals. 



Mice inoculated subcutaneously usually die in about 

 twenty-four hours, and enlargement and congestion of 

 the spleen are very noticeable. An infected guinea-pig 

 generally dies in about thirty-six hours and usually shows 

 no symptoms until the last, when it may suffer from rigors, 

 with high temperature, convulsions, and staring coat. 

 Post-mortem, the muscular tissue is found to be pale and 

 oedematous, the spleen is enlarged to two or three times 

 its normal size and is highly congested and very soft, and 

 minute haemorrhages may occur in the serous membranes. 

 Microscopically, bacilli are found throughout the spleen, 

 and are often so numerous that in a stained preparation 

 there appear to be more bacilli than tissue. Large num- 

 bers are also present in the blood and lungs, fewer in the 

 liver and kidney ; in the latter organ they are almost 

 confined to the glomeruli (Plate IV, 6). Immediately 

 after death, however, comparatively few bacilli may be 

 met with in the blood, the heart, and great vessels. 



The spread of the disease in nature seems to result 

 from the ingestion of spores while the animals are feeding. 

 Although the bacilli without spores would be destroyed 

 by the acid gastric juice, this is not the case with the 

 spores, which are probably generally developed from the 

 organisms present in the bloody discharges of a stricken 

 animal, and are distributed by wind and flood, and in this 

 way may infect large tracts of pasture. Crows and foxes 



