Among the many interesting and valuable papers presented at the Seventh International Congress of Hygiene and Demography recently held in London, the one presented by Dr. E. Roux, one of Pasteur's principal co-workers, deserves special mention.
Pasteur's treatment of hydrophobia consists in producing, during the period of incubation of the disease, an artificial immunity in the person bitten by a rabid animal. This is accomplished by inoculating the individual on successive days with virus of different degrees of activity, commencing with a very attenuated virus and using on each succeeding day a virus of greater intensity.
The virus is obtained in the following manner: With the most complete antiseptic precautions, a rabbit is trephined at the back of the skull, and a few drops of the cerebro-spinal fluid of an animal suffering from rabies is injected under the dura mater. The piece of bone removed is then returned and the