242 GENERAL THERAPEUTICS FOR VETERINARIANS 



in consequence of the strict enforcement of veterinary police regulations, the 

 number of cases rapidly decreased, until in 1880 there were 1781 and in 1883, 

 1187 cases. A compilation made by Kitt shows that in England the number 

 of cases decreased only with the adoption of stringent protective regulations 

 in 1878 from 4590 to 2144 in 1879 and to 1200 in 1882. In Bavaria, following 

 the introduction of the Imperial veterinary sanitary laws, the number of cases 

 decreased from 846 in 1846 to 281 in 1883. In Baden, where from 1870 to 

 1880 0.2 per cent, of all the cattle died yearly from lung plague, there was 

 not a single case in 1885. 



The answer to the question as to the value of vaccination for lung plague 

 depends principally upon whether it is to be used only for immunizing individ- 

 ual animals or to combat an outbreak of the disease in a herd or in a district. 

 In this connection the following statements can be made: (1) Vaccination, 

 as a rule, confers a high degree of immunity upon individual cattle. (2) The 

 value of vaccination as a veterinary police measure for combating lung plague 

 is, on the contrary, doubtful. Experience has many times taught that not 

 all vaccinated cattle acquire an immimity, but that about 2 per cent, remain 

 susceptible to the disease. These apparently immune cattle, when they subse- 

 quently suffer a latent attack of the disease, are a continuous source of infec- 

 tion for healthy animals, especially in regions where the traffic in cattle is 

 extensive (province of Saxony). Furthermore, lung plague sometimes runs 

 Buch a mild course that no symptoms of disease are apparent and the recogni- 

 tion of the disease in time for the vaccination of the herd is not possible. The 

 length of the period of incubation also often prevents a prompt diagnosis or 

 early vaccination. As a method of combating the disease, slaughter of the 

 infected herds is much more rehable than vaccination. 



Rabies. — Pasteur announced in 1884 that the virus of rabies could be 

 gradually weakened by inoculating it from the dog into a monkey and then 

 successively from monkey to monkey. Virus attenuated in this way and in- 

 jected subcutaneously or under the dura mater, after trepanation of the 

 cranial cavity, does not produce rabies in the dog, but on the contrary renders 

 the animal immune to artificial or natural infection with the disease. Subse- 

 quently, Pasteur published another method of immunization in which the 

 dried spinal cord of a rabid animal is used as the vaccine. The spinal cord of 

 a rabbit affected with rabies is removed under aseptic precautions up to the 

 lower end of the cerebellum, together with all of its coverings, and cut into 

 pieces 6 cm. long, which are suspended on threads in bottles. The bottoms 

 of the bottles are covered to a depth of 1.5 cm. with small pieces of caustic 

 potash and their openings are closed with cotton plugs. They are kept at a 

 constant temperature of 20° C. After 3 to 4 days, the pieces of spinal cord 

 are dried into ribbon-like, very friable strips, the toxicity of which gradually 



