PROPHYLACTIC IMMUNIZATION OR VACCINATION 



641 



emulsion are injected beneath the dura of a normal rabbit. In large 

 institutes two or more rabbits are injected daily. The inoculation is 

 quickly and easily performed by trephining a small area in the median 

 line of the forehead and injecting the emulsion beneath the dura mater 

 with a syringe. The whole operation must be carried out in an aseptic 

 and practically painless manner. 



2. After inoculation the animals are placed in clean cages; in from 

 six to eight days paralytic symptoms of rabies appear, followed in three 

 to four days by death. The hair is then sprayed 



with a solution of lysol and the skin removed. 

 The cord and brain are then extracted under 

 aseptic precautions. The cord is severed just 

 below the medulla, a portion is snipped off into 

 sterile bouillon for culture, and then divided into 

 two equal pieces which are suspended by sterilized 

 silk threads in a sterile glass jar containing flakes 

 of caustic potash (Fig. 132). The medulla is 

 placed in a sterile dish, and is used to continue 

 the inoculations, as was previously described. A 

 postmortem examination is finally performed, and 

 any cord in which the animal is found diseased or 

 in which the culture of the cord shows bacterial 

 contamination is rejected. 



The jars with suspended cords are kept in a 

 special room at a temperature of about 20 to 25 C. 



3. After a suitable period of drying pieces of 

 cord are prepared for injection. This is performed 

 in various ways at different laboratories; no at- 

 tempt at exact dosage is made. In the New York 

 Board of Health laboratories 1 cm. of the cord is 

 thoroughly emulsified in 3 c.c. of sterile saline 

 solution, the process being conducted in an aseptic 

 manner. If the material is to be shipped, an 



addition of 20 per cent, of glycerin and 0.5 per cent, of phenol is 

 made. 



Administration of 'the Vaccine. Injections are given with a sterile 

 syringe. The abdominal region of the patient is bared, a spot touched 

 with tincture of iodin, wiped with alcohol, and the injection given sub- 

 cutaneously. Keirle does not vary the dose according to the age, both 

 the old and the young receiving the same dose. At times the injection 

 41 



FIG. 132. PREPARA- 

 TION OF RABIES 

 VACCINE. 

 Note the cords 

 suspended within the 

 jar by means of sterile 

 silk threads; sticks of 

 sodium hydroxid to 

 absorb moisture and 

 hasten desiccation. 



