The cellar being useless, the door had been closed, and the only vent for the pestiferous gases was through the floor, which was open in several places. The family being immediately removed, all the sick became convalescent from the time they ceased to breathe the air of the place. The owner of the house hired two men to empty the cellar. These men having ripped up the floor, and placed a pump in the deepest part of the water, evacuated the cellar to the dregs in one day. On the second day after the execution of this task, one of these men was seized with a chilliness, succeeded by an ardent fever, which terminated with the usual symptoms of yellow fever; namely, hæmorrhages, yellow skin and petechiæ, and proved fatal on the third day from the attack: the day following the seizure of the first, the second man was attacked with similar symptoms, and died on the seventh day of the disease, with the black vomit, in addition to the ordinary symptoms of the yellow fever. These examples may suffice to illustrate the operation of that febrile poison which arises chiefly from the decomposition of vegetable matter. The poison derived from the putrefaction of animal matter is still more pernicious: its effects are more powerful in degree, and worse in character; it operates more intensely on the nervous system, and less on the vascular; and the fevers it produces are invariably of the typhoid type, and of the continued form. Without doubt, a febrile poison, purely of animal origin, in a high degree of concentration, would kill instantaneously; and when not intense enough to strike with instantaneous death, it would produce a continued fever with the typhoid characters, in the greatest possible degree of completeness and perfection. And this appears to afford the true solution of the origin of the plague. The more closely the localities are examined of every situation in which the plague prevails, the more abundant the sources of putrefying animal matter will appear, and the more manifest it will become, not only that such matter must be present, but that it must abound. And this also is one of the truths which was known to the observers of former times, but which has been forgotten. Were it not that the professional reading of an age, is bounded by as strict a line as that which divides century from century; were it not that no one reads back beyond the authority which happens to give to the day its prevailing doctrines; were it not that the great repository of facts treasured up in the volumes of the close observers, though sometimes the bad reasoners of former days, thus becomes neglected for the dogmas of some modern writer, who reasons as ill, and who observes less, the notion that vegetable malaria produces only intermittent fever, never could have become so prevalent as it is at present, nor could the influence of animal malaria ever have been so entirely overlooked. But it chanced that Cullen, in his definition of