OF LIVING BONE AND DRIED DEAD BONE. 143 



matter were removed from the compact tissue, we 

 should have left a web or net-work of capillary 

 vessels having longitudinal meshes. 



2OO, Of living bone and of dried dead bone. The 



authors of many manuals and treatises on minute 

 anatomy have described the structure not of living or 

 recently dead bone, but of bone which has been dead 

 for a long time and has undergone dessication. The 

 student is thus led to acquire a notion of the struc- 

 ture of bone as imperfect and incorrect as would be 

 that which he would form of the structure of skin, 

 nerve, or muscle, were he to examine dried specimens 

 of these tissues only. We desire to learn how tissues 

 live and grow and decay in the living body ; but the 

 structure of bone and teeth has been described, not 

 as it may be demonstrated in these tissues when they 

 are fresh, but only, as it appears, after the textures 

 have been altered by death, and after they have been 

 comp^tely deprived of their living matter. 



2O1. An elementary part of dead dried bone. An 

 elementary part of fully-formed dead and dried bone 

 consists of a space (lacuna), occupied in the recent 

 state with bioplasm, and surrounded by a portion of 

 hard osseous tissue which is traversed by numerous 

 pores or channels (canaliculi) passing from one little 

 space (lacuna) in a tortuous manner to adjacent lacunae. 

 2O2. An elementary part of living bone. An 

 elementary part of fully-formed living lone consists of 

 a mass of bioplasm surrounded on all sides by, and 

 continuous with, a thin layer of soft formed material, 

 which passes uninterruptedly into the hard calcified 

 formed ma'erial (matrix or intercellular substance of 

 authors). This hard material is in the fu!ly formed 

 bone penetrated everywhere by very fine channels 

 (canaliculi) through which the nutrient material 

 passes towards the masses of bioplasm ; for, as the 

 hard material in its fully formed s'.ate is almost im- 

 permeable, nutrient fluid could not reach the bioplasm 



