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ticular modes of treatment must be all taken on credit. They may or may not be true; but the reader has no means of testing their accuracy except seeing them applied to practice. Without impugning the truthfulness of the writers, there may yet be grounds for questioning the accuracy of their conclusions. What proof is there that they have not fallen into a mistake in forming an estimate of causes and their effects? Several medical men will watch simultaneously the progress of a case of illness, enjoying equal opportunities of studying its phenomena; yet if you come to ask them afterwards their opinion of the effects produced by any particular remedy employed in the treatment, the probability is that the estimate formed by each will be very different. One will consider it beneficial, another inefficient, a third positively injurious. How is this to be accounted for? Simply by the differences existing among them as to intelligence, closeness of observation, and accuracy in drawing deductions. I have often been struck at the various opinions expressed by the members of the class, when making a physical examination of a patient, as to so simple a thing as the comparative resonance of the percussion sound in two sides of the chest. Here is a matter upon which it might be thought that the merest tyro in the profession could scarcely fall into a mistake, and yet the contrary is the fact. Differences in the mode of percussion, in the degree of force employed, in the attitude of the patient, and in the tension of the Thoracic parieties will sensibly alter the result, and lead to innumerable errors. And if this be true when the point to be determined is merely the physical condition of a part, can it be a matter of surprise that mistakes should occur when the question for consideration relates to some vital phenomenon of an obscure character, and involves a comparison of the patient's state at two different periods of time?
Systematic courses of lectures, as given in connexion with schools of anatomy, have this advantage over text-books, that being given vivâ voce, the teacher is able to introduce into his lectures every new discovery as it comes out, and so to keep his pupils up to the standard of medical know-
