In making the section of the bones, the saw ought to be applied to the humerus transversely just at the commencement of its condyloid projections, and to the radius and ulna, at least at a level with the base of the coronoid process of the ulna. But while removing enough, we must not be led into the error of removing too much. If this is done, as was done by Sir Philip Crampton in his first case, and as happens occasionally of necessity in cases of excision for gunshot wounds or other accidents, much of the power of the arm is lost as a consequence of the shortening and excessive mobility. A mistaken pathology sometimes deceives in the examination of the state of the bones, and causes an unnecessary amount to be removed. For in many cases of disease the bones in the neighbourhood of the joint are stimulated to an excessive amount of what is in reality Nature's effort at repair, and while the cartilaginous surfaces are denuded of cartilage, soft, and porous, the bones close by are roughened with a stalactitic-looking growth, projecting in knobs and angles. Now, if this be mistaken for disease and removed, too much will almost certainly be taken away, and the result will be unsatisfactory. Much less care need be taken exactly to discriminate and remove the diseased soft parts; indeed they may be left alone; the synovial membrane in a state of gelatinous degeneration sometimes presents a very formidable appearance of disease, but if the bones be properly removed, all this swelling will soon go down, and a healthy condition of parts succeed, without any clipping or paring on the surgeon's part. _Operation._--The back of the joint is of course chosen for the seat of the incisions, both because the bones are there just under the skin, and because the great vessels and nerves lie in front of the joint. The form and number of the incisions vary considerably, and ought to vary according to the nature of the case and the amount of disease or injury. Though it is now little used, for historical interest I retain the description of the H-shaped incision (Plate III. fig. C.), used first by Moreau, and re-introduced by Mr. Syme, and used by him for most of his very numerous cases.