72 THE MODE OF REPRODUCTION AFTER DEATH 



place, for the separation, by the process just described, of more 

 or less numerous portions of its surface. When the entire peri- 

 osteum has separated from the shaft, it carries with it those mi- 

 nute 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 haversian canals ; the gradual en- 

 largement 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 de- 

 velopement, 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 rapi- 

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

 bone will also depend very much upon the same circumstances ; 

 for, if the centres of formation of the new shaft are separated 

 from one side only of the old bone, then an unshapely mass of 

 new bone is thrown out on the same side, for the purpose of 

 strengthening the part during the time necessary for shooting 

 across the bridges of bone which are to supply that side of the 

 new shaft, for the formation of which no osseous centres had 

 been separated. Every possible modification, resulting from 

 these principles, may be observed in looking over series of ne- 

 crosed long bones. 



A remarkable fact in connection with cloacae is, that they are 

 almost invariably opposite a smooth or unaltered portion of the 

 surface of the dead shaft. They result from the pus thrown off 

 from the granulating internal surface of the new shaft making its 

 way to the exterior, by those parts not yet closed, in consequence 

 of having been opposite to portions of the old shaft, which had 

 not afforded separated osseous centres. After the new shell has 

 gained its full strength, the cloacae, like sinuses of the soft parts, 



