Licence: Public Domain Mark
Credit: Outlines of human pathology / by Herbert Mayo. Source: Wellcome Collection.
Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.
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![even in channels within the callus*. The callus adheres to the surfaces of the bone above and below the fracture: it is (towards the close of the third period) covered with a sepa- rable membrane, which is continuous with the periosteum : there is no periosteum between the callus and the bone, but where the callus begins, the periosteum terminates in the membrane covering the latter. In the mean time, the lymph, by which the ends of the bones are glued together within the callus, undergoes little change. The work of restoration, at present, is all external. The quantity of callus formed bears a strict proportion to the quantity of injury. An oblique fracture, or a comminuted fracture, or a fracture which has been overlooked for two or three days, has a greater proportion of callus than a transverse fracture which has been set at once. [c. 35.] 4. The fourth period extends from the twentieth or twenty-fifth day to the thirtieth, fortieth, or sixtieth, ac- cording to the age and vigour of the patient. During this period, the provisional callus ossifies; and, at its expi- ration, the broken limb has already sufficient strength to admit of being used. As yet, however, no direct ossific union has taken place between the broken ends. If the ossified callus is at this time divided, the extremities of the bones are found to move easily upon each other, being united by a layer of soft vascular substance alone, which is continuous on the one hand with the external callus, and on the other with the thickened medullary membrane, [c. 1.] * There are four opinions as to the source of the provisional callus : that it is produced by the periosteum; that it is an exudation from the extremities of the broken bone, particularly from the medullary mem- brane; that it is derived by direct growth from the animal structure of the bone; that it originates in an infiltration of the textures adjacent to the bone. The first is the opinion of Duhamel, the second that of Haller, the third that of Baron Larrey, the fourth that of Dupuytren and of Mr. John Bell. The account in the text is drawn up after M. Sanson's account of Dupuytren's observations (Journal Universel des Sciences Medicales, tome xx), and some experiments of my own, published in the Medical and Physical Journal several years ago.](https://iiif.wellcomecollection.org/image/b21066735_0040.jp2/full/800%2C/0/default.jpg)
