other vessels which circulate through bone. Internally, the cellular tissue and medullary cavity of bone is lined by a delicate membrane, improperly termed by some anatomists Internal Periosteum. This membrane is highly vascular, and is connected with the periosteum by the interstitial filaments or processes described above.
On considering the close connection which exists between the surfaces and intimate structure of bone through the medium of the periosteum, it will be understood how diseases of this membrane may often be confounded with those of the osseous tissue itself.
Although this close connection does exist, and although disease frequently extends from the periosteum to the proper tissue of bone, we are not warranted, in the present state of our knowledge, to assert, that it is through the medium of the periosteum, that all or even the greater number of the morbid conditions of bone originate. We meet with cases in practice, where the periosteum is affected with disease, even of a malignant character, in which the bone itself remains healthy.
Having offered these few general remarks, I shall now proceed to describe those morbid affec-
