492 BACTERINS, SERUMS — VACCINES — ANTITOXINS 



A series of spinal cords taken from rabbits dead of " fixed virus " 

 are cut into segments and suspended in sterile glass jars containing 

 caustic potash. These jars are kept at approximately 22° C. The 

 cord, when taken out at the end of the first 24 hours, is found to be 

 almost as active as the fresh untreated cord ; the cord removed at 48 

 hours, is slightly less active than that removed 24 hours before ; and 

 the diminution in virulence, though gradual, progresses regularly and 

 surely until at the end of the eighth day the virus is inactive. 



The system of treatment given at the different laboratories varies. 

 Some allow the cord to desiccate for 14 days. The system given here 

 is the one used in the Hygienic Laboratory of the Public Health and 

 Marine Hospital Service, Washington, L). C. It also corresponds 

 closely with that used in Berlin. 



Black Leg Vaccine. To Arloing, Comivin and Thomas belongs 

 the honor of first discovering that animals may be protected against 

 black leg by inoculation with more or less virulent material obtained 

 from animals which have died from black leg. They found that 

 hypodermic injection of minimal doses of fluid from a black leg 

 tumor did not necessarily result in death, but frequently produced a 

 mild attack of the disease, unaccompanied by any swelling, and that 

 animals thus treated were afterwards possessed of a very high degree 

 of resistance to the disease. The method of preparing black leg vac- 



