The germs of the disease are easily destroyed by moderate heat, strong light, and most disinfectants, but are apparently capable of preservation for long periods when protected from such agencies; and hence the disease is capable of being transported from place to place by the agency of dirty clothing, infected rags and such like, but the characteristic which most embarrasses our efforts to deal with the malady is the fact that plague is a disease not only of man, but also of many other animals; and that rodents in particular are specially liable to be affected by it, and are in fact generally seriously involved before an epidemic has attained any serious spread amongst human beings. Not infrequently, the first warning of an impending epidemic is the discovery of dead and dying rats in large numbers; and the best considered plans of dealing with the disease are necessarily constantly defeated by the impossibility of extending to these proverbially secretive and cunning animals the measures of isolation and disinfection that are indispensable to success. It is obviously to little purpose to disinfect the room in which a human patient has died, when in hollows in its walls, roof and floors are hidden whole families of rats in every stage of the disease; and it can avail little to isolate the comparatively few human patients, while hundreds of infected rats are left to wander about at will. Luckily, the infection of plague requires close contact to secure transmission, and there is practically no danger of contracting the disease in the ordinary open-air intercourse of life. From what has been said, it will be seen that for Europeans resident in plague-stricken towns personal prophylaxis is a comparatively simple matter, as it is instinctively carried out as a matter of national habit. There is comparatively little danger in entering infected buildings during the day, or even in handling the sick, but unless it be a part of his duty to do so, it is better for the European to avoid passing through the infected portion of the town; to keep a keen eye on the health of his servants; and generally to restrict, as far as possible, association with the native community. The house should be kept freely open to air and light, avoiding the closing of doors and windows to exclude the heat, as in doing so we reproduce the domestic habits which cause the natives to suffer so severely. If the weather admit of it, it is better to sleep in the open; and should any mortality among rats be observed within the dwelling, there should be no waiting for any second hint, but the place should be vacated at once, and thoroughly disinfected; nor is it well to return to it for at least three weeks. Among the very small number of cases in which Europeans have fallen victims to the disease, neglect to take timely warning from the death of rodents within the house has occurred in more than one instance directly reported to the writer.