REPRODUCTION OF BONE. 469 



kind, or in the Hunterian sense in which it is employed, as a 

 mode of expression for an action, the details of which have 

 not been recognised. 



By the enlargement of neighbouring Haversian canals, and 

 the consequent removal of all the osseous substance of a por- 

 tion of bone, an ulceration is produced, or a piece of dead or 

 dying bone is separated from the living organ. A stratum of 

 what, in the language of surgical pathologists, is named 

 granulations, divides the dead from the living, and ultimately 

 casts the dead off, by assuming a free surface towards it, 

 throwing pus into the inter-space. 



When the entire shaft of a bone is attacked by violent in- 

 flammation, there is generally time, before death of the bone 

 takes place, for the separation, by the process just described, 

 of more or less numerous portions of its surface. When the 

 entire periosteum has separated from the shaft, it carries with 

 it those minute portions of the surface of the bone. Each of 

 these is covered on its external surface by the periosteum, on 

 its internal by a layer of granulations, the result of the 

 organised matter which originally filled the inflamed Haver- 

 sian canals ; the gradual enlargement and subsequent blending 

 of which ultimately allowed their contained vascular contents 

 to combine with the layer of granulations just described ; and 

 to form the separating medium between the dead shaft and 

 its minute living remnants. These minute separated portions, 

 after having advanced somewhat in development, appear, when 

 carelessly examined, particularly in dried specimens, to be 

 situated in the substance of the periosteum, and have been 

 adduced by the advocates of the agency of that membrane in 

 forming new bone, as evidences of the truth of their opinions. 



In proportion to the equal manner in which these living 

 portions of the old shaft are arranged over the whole internal 

 surface of the periosteum, will be the facility and consequent 

 rapidity in the formation of the new shaft. The shape of the 



