is due. This is an anaërobic bacillus which forms large oval spores.
The ætiology of the disease was first clearly established by the researches of Arloing, Cornevin, and Thomas (1880 to 1883).
Strebel, in 1885, published the results of protective inoculations made in Switzerland in 1884. The inoculations were made in the end of the tail with two "vaccines" with an interval between the two of from nine to fourteen days. The vaccines were prepared by exposure to heat, as recommended by Arloing, Cornevin, and Thomas. The most favorable season for inoculations was found to be the spring, and the most favorable age of cattle for inoculation from five months to two years.
In seven Swiss cantons 2,199 cattle were inoculated; 1,810 inoculations were made among animals which were exposed in dangerously infected pastures. Of these but two died, one two months and the other four months after the protective inoculations. Among 908 inoculated cattle, which were pastured with 1,650 others not inoculated, the mortality was 0·22 per cent, while the loss among the latter was 6·1 per cent. The following year (1885), according to Strebel, the number of inoculations, exclusive of those made in the canton of Bern, was 35,000. The losses among inoculated animals are reported as having been about five times less than among those not protected in this way.
In the Bulletin of the Central Society of Veterinary Medicine of France (1893) Guillod and Simon give the results of 3,500 inoculations made since 1884. The mortality among cattle in the region where these inoculations were practiced had been from ten to twenty per cent, but fell to 0·5 per cent among the inoculated animals.
The success of Pasteur's method of prophylaxis against hydrophobia is now well established, although the specific germ of this disease has not yet been demonstrated.
Perdrix (1890), in an analysis of the results obtained at the Pasteur Institute in Paris, calls attention to the fact that the mortality among those treated has diminished each year, and ascribes this to improvement in the method. He says:
"At the outset it was difficult to know what formula to adopt for the treatment of each particular case. Upon consulting the accounts of the bites in persons who have died of hydrophobia, notwithstanding the inoculations, we have arrived at a more precise determination as to the treatment suitable for each case, according to the gravity of the lesions. In the cases with serious wounds we inject larger quantities of the emulsion of cord and repeat the inoculations with the most virulent material. For the bites upon the head, which are especially dangerous, however slight their apparent gravity may be, the treatment is more rapid.
