"Who shall decide when doctors disagree?" says the poet, with as close accordance with a general truth as reason and poetry require. Yet we shall always find, even in the case of the disagreement of doctors, criteria by which rational decision may be reached. In the first place, the opinions of individual doctors, as well as of persons not doctors, are not of equal weight, as emanating from men of learning, conversant with the class of subjects under consideration, and qualified to be experimentally satisfied, if question of experiment there be, of the results which they have obtained. In the next place, personal feeling and pecuniary interest may enter into the determination of questions and, giving bias, place the decider of them in a non-judicial attitude of mind. Other things being equal, the fact of the majority, and that a large majority, on one side, is an element enabling an