324 CLINICAL BACTERIOLOGY. 



twelve days old, in part ; and the others, successively less 

 and less. Through successive inoculations with these 

 gradations of spinal cords Pasteur established complete im- 

 munity in dogs. Upon the basis of these facts Pasteur 

 proceeded to the vaccination of human beings therapeuti- 

 cally against rabies. In view of the long period of incuba- 

 tion of rabies in human beings the attempt was justified and 

 hopeful ; for, if it were possible to establish immunity 

 through vaccination immediately after the bite of the rabid 

 animal and before the period of incubation had elapsed, 

 then it could be hoped that the disease would not break out. 

 The results have completely confirmed Pasteur's anticipa- 

 tions. At first, the injections were so made that on the first 

 day the spinal cord of rabbits kept for fourteen days, on the 

 second day that of rabbits kept for thirteen days, and so on 

 for ten days until the cord of rabbits kept for five days was 

 reached, were successively injected subcutaneously into the 

 subject to be treated (methode simple). Pasteur, however, 

 soon recognized that this procedure was not sufficient for 

 the severe cases with deep and numerous wounds. 



Vaccination is at present practised in the Pasteur Insti- 

 tute in the following manner (methode intensive) : A piece 

 of spinal cord about three millimeters long is rubbed up in 

 sterile bouillon and injected beneath the skin in the hypo- 

 chondrium, and on the first day in the morning medulla 

 fourteen and ten days old an injection being made on 

 either side in the evening medulla twelve and eleven days 

 old ; on the second day in the morning medulla ten and 

 nine days old, in the evening medulla eight and seven days 

 old ; on the third day two injections of medulla six days 

 old, and from now on an injection every twenty-four hours 

 of the more toxic spinal cords up to that three days old. 

 With the spinal cord three days old a new series is begun, 

 commencing with the medulla five days old. Upon this 

 succeeds a third, and possibly a fourth, series of like 

 character. 



Vaccine may be prepared also by dilution with sterile 

 water (Bardach) instead of by desiccation. This fact indicates 

 that also in the dried spinal cord the virus is not actually 

 attenuated, but only diminished in amount. As a matter 

 of fact, Pasteur, after injecting desiccated medulla into a 

 guinea-pig and the animal dying after thirty days, observed 

 the medulla of this animal destroy a second guinea-pig 



