IMMUNITY AND ANTITOXINS 257 



Pasteur's treatment of rabies by inoculation of emulsions of 

 dried spinal cord is, therefore, a " vaccination " of attenu- 

 ated virus, resulting in antitoxin formation, to the further 

 protection of the individual against rabies. 



One further example of the modern application of the 

 principles of active acquired immunity may be shortly men- 

 tioned. We refer to the cholera and plague vaccinations. 

 The vaccination in small-pox is an inoculation of the virus 

 of the disease ; the rabies inoculation is a transmission of the 

 vital products of the disease attenuated ; the plague and 

 cholera vaccinations are inoculations of pure cultures of living 

 virus from outside the body. Inoculating cholera virus 

 against cholera has been made illegal, as variolation was 

 in 1840. But Haffkine has prepared two vaccines. The 

 weak one is made from pure cultures of Koch's spirillum of 

 Asiatic cholera, attenuated by growth to several generations 

 on agar or broth at 39 C. The strong one is from similar 

 culture the virulence of which has been increased. One 

 cubic centimetre of the first vaccine is injected hypoder- 

 mically into the flank, and the second vaccine three or four 

 days afterwards. The immunisation is prophylactic, not 

 remedial, and its action takes effect five or six days after 

 the second vaccine has been injected. 



In plague the same plan has been followed. Luxurious 



