50 



bone-cells through the canaliculi : this even happens in the bones of 

 mummies, where, as Mr. Smee has shown, the bone-cells are fre- 

 quently full of the bituminous and other matters with which the 

 bodies were prepared. The structure between the bone-cells, which, 

 with perfect consistency, may be called the intercellular substance, 

 by an ordinary magnifying power, appears to be homogeneous ; but 

 under higher powers, as Mr. Tomes has described, it will be found to 

 be minutely granular, the granules varying in size from -g^s to -r^-my 

 of an inch : they can be readily seen in a bone which has long been 

 subjected to the action of boiling water or steam, the granules being, 

 in fact, the true ossific matter of the bone. If a vertical section be 

 prepared, in a similar manner to the horizontal one just described, 

 and be examined with the same power, we shall find that the Ha- 

 versian canals, for the most part, take a longitudinal direction, and 

 that the bone-cells also assume a linear arrangement. Some few of 

 the Haversian canals run at right angles to the section, and these 

 communicate with the openings previously noticed,JDoth on the ex- 

 terior and interior of the shaft. Thus much may be said to compose 

 the hard part of bone ; we must now turn our attention to the soft 

 part. This, as has been before stated, consists of the periosteum, 

 which invests the outer, and of the medullary membrane, which invests 

 the inner surface, lines the Haversian canals, and is continued from 

 them, through the canaliculi, into the interior of the bone-cells, and 

 of the cartilaginous or other matrix which forms the investment of the 

 minute ossific granules. The earthy matter of the bone may be rea- 

 dily shown by macerating the section for a short time in a dilute solu- 

 tion of caustic potash ; but the granules, according to Mr. Tomes, 

 may be best obtained by subjecting bone to high-pressure steam, or 

 to a red heat, till the animal matter is removed, the mass may then be 

 reduced to powder, and a little dilute acid added, which will destroy 

 all the broken granules before the entire ones are at all affected. 



The animal matter may be procured by using dilute muriatic acid 

 instead of caustic potash, when the earthy matter will be removed, 

 and the section will exhibit nearly the same form as when the earthy 

 constituent was present ; and when viewed microscopically, it will be 

 noticed that all the parts characterizing the section, previous to its 

 maceration in the acid, will be still visible, but not so distinct as when 

 both constituents were in combination. When, however, the animal 

 matter is removed, the bone will not exhibit the cells and the ca- 

 naliculi, but will be opaque and very brittle, and exhibit nothing but 

 the Haversian canals and a granular structure. 



