664 A MANUAL OF BACTERIOLOGY 



To prepare the anti-rabic vaccines, a rabbit is inocu- 

 lated subdurally with an emulsion made from the medulla 

 of a rabid dog. When the animal dies, a second rabbit is 

 similarly inoculated from the first, and the passage through 

 rabbits is continued until a " fixed " virus is obtained, 

 with which the first symptoms appear on the seventh or 

 eighth day, and which kills with certainty in about ten 

 days. This having been attained, two or three rabbits 

 are inoculated subdurally every day, so that there is a 

 daily supply of animals dead of the disease. The spinal 

 cord is removed with aseptic precautions, cut into con- 

 venient segments, and suspended in bell jars containing a 

 layer of solid caustic potash at the bottom, which serves 

 to desiccate them. The jars are dated, and preserved in 

 glass cases in a dark room, kept at a constant temperature 

 of about 23 C. In Paris the vaccine fluids are prepared by 

 triturating portions of the dried cords in sterile broth, 

 so as to form an emulsion 1 cm. of cord in 5 c.c. of sterile 

 broth, of which 1 c.c. (i.e. 2 mm. of cord) forms a single 

 dose. At the commencement of treatment the cords 

 which have been dried for fourteen days are used, at the 

 end of treatment those which have been dried for only 

 three days ; the latter are much more virulent, and would 

 communicate the disease but for the previous treatment. 

 The rabbits employed should all be of the same weight 

 (2| kilogrammes in Paris) ; if the rabbits are small, a 

 slightly shorter period of desiccation of the cords would 

 be necessary. The treatment varies in duration according 

 to the severity of the case, which is gauged by the number 

 and situation of the bites and by the species of animal. 

 Bites on exposed parts are regarded as much more serious 

 than those through clothing, and on the face, where 

 efficient treatment is difficult, than on the hands, and 

 wolf bites than dog bites. 



The doses are injected subcutaneously in the flank, 



