In spite of its brilliant success and the great boon it has been to humanity, the Pasteur treatment is not an ideal one. Its success does not consist in an entire extinction of rabies, but merely in the reducing of its evil results; its success is indeed based on a preservation and propagation of the germ and a continuous danger of infection of new subjects; finally, the proposition to end the disease by passing the whole canine race through the treatment, is open to the objections that this would require a fabulous outlay, and that even then some rare cases are not found to be fully protected. To continue the disease, when it may be exterminated, and to palliate its results by the treatment of generation after generation of dogs, must be promptly condemned by the political economist, to say nothing of the consideration of probable human infection. _Orrotherapy._ It is not surprising that essays were made in the line of serum treatment. Babes and Lepp in 1889 had some encouraging results in transferring the blood of an immune animal into a healthy one. But Tizzoni, Schwarz and Centanni have especially worked out this method. These have shown that the blood serum of immunized animals destroyed the virulence of the rabic poison, whether mixed with it before injection, or injected with it, or injected within twenty-four hours afterward. A very small amount of the serum is required and though delayed until the end of the first half of the incubation period, it is only necessary to multiply the amount by six or eight times. In this it has a great advantage over the antitoxin of diphtheria or tetanus, the former of which has to be multiplied 20 to 100 times, and the latter 1000 to 2000 times in the later stages of incubation. Further, it is possible by drying to secure the serum in a permanent form which will remain active for a length of time if secluded from air and light. This has the decided advantages over the Pasteur treatment, (1) that it employs the antitoxin already formed instead of waiting for its formation in the body of the subject injected with the attenuated virus, and (2) that it does not introduce into the system a virulent germ capable of propagating in a favorable medium, but only an agent which is antidotal to that germ. It has the disadvantage as compared with Pasteur’s method that its action is purely therapeutic in the sense of acting as an antidote, while it produces no permanent immunity. It does not like the toxins educate the cells to produce an encrease of antitoxin, and it can only protect so long as it remains in the system. Whenever it is eliminated or destroyed, the susceptibility to rabies returns. Hence it is important to continue its administration as long as the microbe remains in the system. As in tetanus and diphtheria antitoxin treatment, it is also important to destroy the microbe and its toxins in the infection wound.