During the last year of the epidemic in Manila it became the rule for us to expect our plague workers to locate and find the identical rat cadaver from which the infected fleas bore the disease to the human victim, provided the spot upon the floor where the patient's sleeping mat had been placed was known. In the better class of houses the rat (sometimes more than one) was found dead beneath the floor, behind some post casing, or in other space caused by double construction. Time and again I have directed the removal of some panel of woodwork, some post casing, or a board of the floor with the full expectation (seldom unrealized) of finding a dead rat or a rat nest. These experiences were positively uncanny at times. In the houses of the poorer class, usually of bamboo and thatch construction, the finding of the rat was less easy and more uncertain, although the nest was repeatedly found, and as related elsewhere the dead rat itself might be found in a hollow bamboo timber, or in the thatch construction of the wall. In a house on Calle Echague, from which a Filipino and his wife were removed, dead, within a few hours of each other, several dead rats were found in the floor (the only piece of double construction in the whole house) within four feet from the spot where the sleeping mats were placed. A rat hole led to the nest and through this hole the fleas from the dead rats found their way to the human victims sleeping on the floor above the encased nest. These instances could be multiplied many times, but there is no longer any special reason to do so, as the rat and the rat-flea are so completely incriminated as to render these repetitions quite unnecessary, however interesting they may be to the plague worker. The danger of pursuing these investigations, to the persons so engaged, must not be lost sight of, and exposure of such nests and rat cadavers should invariably be preceded by thorough spraying of the place, and particularly of the spot where tearing out of double construction is to be done. I know of no more dangerous employment than this, both for laborer and bystander. CHAPTER IV ITS DIAGNOSIS AND TREATMENT It was not my original intention to include the subjects of diagnosis and treatment in this presentation, except in so far as I have already referred to them in the relation of my Manila experiences in the preceding pages. I have decided, however, to add a chapter upon Diagnosis and Treatment, for the sake of completeness. No attempt will be made to present these subjects in the orthodox way. Rather, my remarks will be confined to such matter as I believe to be thoroughly practical and relevant.