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power of secreting osseous substance and of forming new bony 

 matter. 



Diihamel, founding on a false analogy, which he supposed to 

 exist between the periosteum and the bone on the one hand, and 

 the bark and wood of trees on the other, was the first to hiy down 

 distinctly the theory that bony matter is formed by the investing 

 membrane of the bones. The experiments and observations of 

 Holler and others on the progress of ossification in young animals 

 were believed, however, to militate against this idea, and tended 

 rather to establish the doctrine, that new bony matter is formed by 

 the pre-existing or old bone. Between these two theories, the 

 opinions of physiologists and surgeons are still pretty equally di- 

 vided. 



The author was lately induced to suspect, from the circumstances 

 of a case of necrosis, that the theory of Duhamel is the true one. 

 In a case of inflammation of the tibia consequent on an injury and 

 terminating in death, of nearly the whole of that bone, amputation 

 became necessary at the dose of five weeks after the accident. On 

 examining the amputated limb, the periosteum of the tibia was 

 found chequered with patches of osseous substance adhering to its 

 inner surface, and covered with a delicate membrane. This obser- 

 vati(m led him to subject the qiiestion to the test of experiment, 

 which he conceives he has accomplished in the following manner. 

 An incision was made in the fore leg of a dog, and a portion of the 

 radius, about two inches long, was removed along with its invest- 

 ing membrane. In the other fore leg the same operation was per- 

 formed, with the exception that the periosteum was carefully dis- 

 sected from the portion of bone which it was intended to remove, 

 and two inches of bone were cut out, its membrane being thus left 

 entire. In six weeks the animal was killed ; when it was found 

 that a large vacuity was left in the radius, where the membrane 

 was removed as well as the portion of bone ; while in the other, 

 where the membrane had been left, the gap was entirely filled up 

 by firm osseous texture, and at this part of the radius the bone was 

 even thicker than elsewhere. The experiment was several times 

 repeated with the same result. In another dog the periosteum of 

 the radius was carefully dissected off as before, but without either 

 disturbing the position of the membrane or removing the subjacent 

 portion of bone ; and a thin metallic plate was passed around the 

 bone between it and the detached periosteum. In six M'cek the 



