VACCINATION. IMMUNIZATION. INOCULATION 231 



in connection with lung plague, foot-and-mouth disease, rinderpest, 

 pox, swine erysipelas, chicken cholera and other diseases. If the 

 contagion of these diseases is introduced into the body through 

 another channel, for example through the skin or subcutis, it will 

 be brought in contact with essentially different living conditions 

 and it will also be absorbed very slowly and in very small quantity. 

 This method of attenuation was formerlj' employed exclusively 

 in veterinary medicine and possesses for the present and for the 

 future of vaccination a continuing importance. At the present 

 time, for instance, the contagion of pox and of foot-and-mouth 

 disease is inoculated in the skin or mucous membrane (cutaneous), 

 and that of lung plague, black leg, swine erysipelas, rinderpest, 

 etc., is injected subcutaneously for the purpose of diminishing the 

 course of the disease. Furthermore, a place for the inoculation 

 is selected as far removed from the heart as possible in order that 

 the resorption will be very slow (end of the tail, tip of the wing, 

 ear). 



3. The influence of the higher degrees of temperature. Every 

 organism has its optimum and its maximum temperature. Higher 

 degrees of temperature weaken the vital energy and finally destroy 

 the organism. It is therefore possible to diminish the toxic effect 

 of the different infectious materials by the use of a certain degree 

 of heat. The reduction of the virulence by heating for 10 to 15 

 minutes at 50 to 55° C. was first demonstrated by Toussaint in 

 connection with the anthrax bacillus. The heating process is of 

 great practical importance in Pasteur's protective anthrax vacci- 

 nation, in which one part of the anthrax bacilli is exposed for 24 

 days to a constant temperature of 42° to 43° C. (first vaccine) 

 and the other part to the same temperature for only 12 days 

 (second vaccine). The animals to be protected are first inoculated 

 subcutaneously with the greatly attenuated first vaccine and 10 

 to 12 days later with the less attenuated second vaccine; they 

 suffer only a mild form of the disease and acquire an immunity. 

 Other infectious materials (black leg, pox) can also be treated in 

 a similar manner. 



