OTHER BACTERIAL DISEASES. 383 



dogs, rabbits, fowls, pigeons, guinea-pigs and horses succumb 

 to the disease by inoculation, in addition to cattle, sheep 

 and goats, in which the disease occurs spontaneously. It is 

 most common among cattle as a spontaneous affection, and 

 quite rarely occurs in sheep and goats. In the horse it is never 

 known to occur spontaneously. So far as known, the bacillus 

 is not pathogenic for man, although this has never been 

 demonstrated ; but no instance has ever been known of man 

 suffering from the infection, even though every opportunity 

 for such infection has been offered. The disease is, therefore, 

 not regarded as injurious to man. The practice of inoculating 

 animals against the disease by a " preventive culture " is widely 

 adopted in the United States. 



In addition to these well-known types of disease of domestic 

 cattle, a few others may be mentioned by name. The hoof 

 and mouth disease is one which, though very common in 

 Europe, is rare or almost unknown in the United States. It 

 is a disease which produces very great destruction in Conti- 

 nental Europe, and has been the subject of a large amount of 

 study. Up to the present time no one has succeeded in dis- 

 covering a microorganism which produces the disease. The 

 general evidence as to the nature of the disease indicates con- 

 clusively that it is a germ disease, but bacteriologists have 

 hitherto been unable to discover its cause. 



Hydrophobia or rabies may also be mentioned as a disease 

 which is most commonly found in dogs, but occurs also in 

 cats, rabbits, and occasionally even in cattle. The cause of 

 this disease has likewise hitherto escaped the discovery of our 

 naturalists. 



Tetanus or lockjaw is a disease of rather rare occurrence 

 among domestic animals, but it may sometimes occur if an 

 animal receive a wound by means of some object that has 

 been lying for a long time in the soil. The cause of tetanus 

 is a well-known bacillus (B. tetanus), which lives normally in 



