HYDROPHOBIA. 



513 



elucidated the fact that the exalted virus contained in the spinal cords 

 of rabbits such as those referred to could be attenuated so as no longer 

 to produce rabies in dogs by subcutaneous injection. This was done by 

 drying the cords in air over caustic potash (to absorb the moisture), the 

 diminution of virulence being proportional to the length of time during 

 which the cords were kept. Accordingly, by taking a series of such spinal 

 cords kept for various periods of time, he was supplied with a series of 

 vaccines of different strengths. Pasteur at once applied himself to find 

 whether the comparatively long period of incubation in man could not 

 be taken advantage of to " vaccinate " him against the disease before its 

 gravest manifestation took place. The following is the record of the 

 first case thus treated. The technique was to rub up in a little sterile 

 bouillon a small piece of the cord used, and inject _it under the skin by 

 means of a hypodermic syringe. The first injection was made with a 

 very attenuated virus, i.e. a cord fourteen days old. In subsequent in- 

 jections the strength of the virus was gradually increased, as shown in the 

 table : 



July 7, 1885, 9 A.M., cord of June 23, i.e. 14 days old. 



day old. 



The patient never manifested the slightest symptom of hydrophobia. 

 Other similarly favourable results followed ; and this prophylactic treat- 

 ment of the disease quickly gained the confidence of the scientific world, 

 which it still maintains. (The principle is, of course, the same as in 

 artificially developing a high degree of active immunity against a bac- 

 terial infection.) 



The only modification which the method has undergone has been in the treat- 

 ment of serious cases, such as multiple bites from wolves, extensive bites about the 

 head, especially in children, cases which come under treatment at a late period of 

 the incubation stage, and cases where the wounds have not cicatrised. In such cases 

 the stages of the treatment are condensed. Thus on the first day, say at 1 1 A.M. and 

 4 P.M. and 9 P.M., cords of 12, 10, and 8 days respectively are used ; on the second 

 day, cords of 6, 4, and 2 days ; on the third day, a cord of I day ; on the fourth day, 

 cords of 8, 6, and 4 days ; on the fifth, cords of 3 and 2 days ; on the sixth, cords 

 of I day ; and so on for ten days. In each case the average dose is about 2 c.c. 

 of the emulsion. 



2 I. 



