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Rh had the advantage of sharing. To Dr. Wilson Fox and Dr. Stephen Mackenzie, I also owe special thanks.

The reader may perhaps look for information upon one topic not alluded to in the following pages, viz., the use of the ophthalmoscope in the study of the action of drugs. It was my intention to include a section on this subject, but I soon found that such a chapter would be merely a collection of contradictory assertions. There is hardly a statement on this subject, made by one observer, which has not been contradicted by some other observer, apparently of equal competence. Unfortunately, such diversity of statement is not confined to this point. A similar discrepancy is observable in the statements which have been made regarding the changes in functional diseases of the nervous system, and the conclusion is unavoidable that many observations on this subject possess a value very disproportionate to the general authority of the observers. Possibly, by some, slight morbid changes have been overlooked; certainly, by others, appearances have been regarded as pathological, which are to be found with equal frequency in normal individuals.

I venture to direct the attention of those occupied in teaching to a point referred to in the appendix—the advantage which it is to students to acquire a knowledge of the use of the ophthalmoscope early in their practical work, instead of, as at present, leaving its acquisition to the last. Strictly, indeed, the use of the instrument, and the examination of the normal fundus, are parts of practical physiology, and might with great advantage be taught in that course in conjunction with the study of the anatomy and histology of the eye. But whether this is done or not, the advantage to the student of a knowledge of the use of the instrument early in his hospital work is very great. Its efficient employment, and still more, a correct knowledge of the nature of the various appearances, are only to be acquired by a considerable amount of practice. When the student, as is now too often the case, only succeeds in seeing the optic disc just before he leaves the hospital, his knowledge of the use of the ophthalmoscope, in most cases, ends with this. Whereas the whole of