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been recently engaging the attention of an ever-increasing number of enquirers. The third still counts a few trustworthy observers, and certainly contains some element of truth, the exact import of which has not yet been determined. For example, the oidium albicans appears in certain forms of malnutrition, while in others its presence has not been detected. Again, how curious to note the appearance of the milk bacillus almost simultaneously with the conversion of an outbuilding of a farm into a dairy.
It is to the second hypothesis that I specially wish to call your attention in its bearing on the causation of disease. Probably no name has become more widely associated with this view of the question than that of Lister. Ever since scientific observation has been associated with the practice of surgery, union of parts by what is technically called "the first intention" has been the great aim of the surgeon. Suppuration, and especially unhealthy suppuration, has marred the results of the most skilful operations. Mechanical and chemical aids have at various times been suggested, and have been more or less successful in the hands of those who introduced them; their subsequent adoption or rejection by the profession has depended very much upon whether, in their more general use, they justified the anticipations which had been formed concerning them. I think they may
