284 OTHER GERM DISEASES. 



under the skin, may be sufficient to cause the disease and death. 

 In the less susceptible animals it requires a larger dose to produce 

 similar results. The lesser susceptibility of such animals as the 

 dog, the horse, the bird, etc., renders them practically immune 

 against spontaneous infection, and the disease occurs among them 

 only as the result of artificial experiments. In man the disease is 

 of rare occurrence, being practically confined to people dealing in 

 or handling hides or wool, and is acquired by them either through 

 abrasions in the skin, when it produces malignant pustule, or by 

 breathing the spores into the lungs, when it is called wool-sorter's 

 disease. 



Preventive Inoculation. Although anthrax is an extremely 

 fatal disease to animals and has, in the past, caused heavy losses 

 to agriculturists, it is a source of less loss to-day than in former 

 years, since it can be fairly well controlled by preventive inoculation. 

 We have noticed in the last chapter that Pasteur demonstrated the 

 important principle of preventive inoculation by his experiments 

 upon anthrax; the discovery has been of great practical value. 

 Cattle can be protected from anthrax by inoculation, and from 

 the time that Pasteur pointed out the method, hundreds of thousands 

 of animals have been thus inoculated and protected. But the 

 protection is not found to be very lasting, and animals must be 

 inoculated about once a year to be thoroughly safe from the disease. 

 This, of course; reduces the value of the inoculation, and confines 

 it to localities where, for special reasons, the disease is quite common. 

 It also explains why the method is not so widely in use now as at 

 first; but, nevertheless, large amounts of the inoculating material 

 have been used in this country as well as elsewhere, and it is thought 

 that immense losses have been prevented by this means since its 

 discovery by Pasteur. 



OTHER GERM DISEASES AMONG ANIMALS. 



No other diseases among animals have acquired so much interest 

 as tuberculosis and anthrax, although several others are known to 

 be produced by microorganisms and are of considerable importance 



