degeneration; but to the living, it is a matter of the utmost importance to learn the true condition of things in the premises. The idea of being eaten alive by myriads of little vermin from which there is supposably no escape, is enough to strike terror to the mind of a patient; but let him know that his disease is of such a nature that (with the _aid_ of the bacilli, perhaps,) a radical change in his manner of living affords great assurance for the hope of its entire eradication, and he has at once an all-sufficient motive for reform. Dr. J. Milner Fothergill, in a letter to the _Philadelphia Medical Times_, referring to Koch’s theory of the origin of tuberculosis, remarks, half jocosely: “Talk of the bitterness of death! It is nothing to the shadowy danger which overhangs us of a tubercle-bacillus getting into one’s pulmonary alveoli in an unguarded moment, and when one’s ‘resistive power’ happens to be impaired. Shadowy in the sense of invisible, not unreal! Is this what is meant by ‘the doom of a great city’? Is the bacillus a relative of the poison-germ which slew Sennacherib’s host in a night? We do not yet know the little creature intimately enough to say. But, really, the horrors which the mind conjures up of the dangers of the bacillus in the future are demoralizing. Suppose, now, that some change of the human constitution should favor the bacillus, just as the potato-field did the Colorado beetle, who had been happily quiet in his dietary of the leaves of the deadly nightshade, but who went on the war-path when the leaves of the other members of the Solanaceæ came within his reach. The imagination fails to conceive what may be the fate of man,——to be slain by a foe more remorseless than any of the plagues of Egypt. Suppose, now, that the bacillus took such a new departure, and got ahead of our ‘resistive power.’ Why, man would be swept off the face of the earth! What an ignominious end, too! Man, in the plenitude of his power over the forces of nature, slain by an insignificant little bacillus!”]