HYDROPHOBIA, rabies, from bite of mad dog, more rarely cat, wolf, or fox; a contagious disease, the result of a specific poison. The great danger lies in the fact that a person bitten by a supposed mad dog imagines or simulates its symptoms, especially if nervous or hysterical; whereas only a few of those bitten by a mad dog take the disease. The average period of incubation is 40 days, but it varies from 15 days to two years. Immediate cauterization or ex cision of the part is the only effective remedy. The Pasteur method of inocu lation is as follows: A rabbit is inocu lated with a fragment of the spinal cord of. a mad dog. The animal is affected with hydrophobia in the space of about one fortnight. A portion of its spinal cord.is employed to inoculate a second rabbit, which also contracts the disease, but more rapidly; the spinal cord of this second rabbit serves to inoculate a third, and so on. When the spinal cord of these animals, which have died of hydrophobia, is suspended in a perfectly dry tube its virulence diminishes by de grees and at last disappears. A collec
tion of these spinal cords, some of them entirely stale and powerless, others more fresh and active, others, again, quite fresh and extremely active, are always kept in readiness. To render a dog in susceptible to rabies he is first inoculated with the stale and powerless specimens, then with fresher and more active ones, and lastly with the most powerful of all, when he becomes quite proof against the inoculation of rabies. Pasteur claimed that by the same process he could pro duce in the human being a correspond ing immunity against hydrophobia. The difficulties that surround the subject will be appreciated when it is remembered that (1) 60 per cent. of people bitten by mad dogs do not develop hydrophobia; (2) the incubation of the disease is some times extremely long, cases having been known to be deferred till two years af ter the bite.