BONE STRUCTURE. 



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scope with a power of 200 linear, we shall see the Haversian 

 canals very plainly, and around them a series of concentric 

 bony laminte, from three to ten or twelve in number. If 

 the section should consist of the entire circle of the shaft, 

 we shall notice, besides the concentric laminae round the 

 Haversian canals, two other series of laminae, the one 

 around the outer margin of the section, the other round 

 the inner or medullary ca^dty. 

 Between the lamime is situ- 

 ated a concentric arrangement 

 of spider-like looking bodies, 

 which have, by difterent au- 

 thors, received the name of 

 osseous corpuscles, lacunce, or 

 bone -cells, according as to 

 whether they were ascertained 

 to be solid or hollow : these 

 bone- cells have little tubes or 

 canals radiating from them, 

 which are termed canaliculi. 

 The averao;e len2;th of the 

 lacunae, or bone- cells, in the 



liuman subject is the l-2,000th ^^g^s.-A transverse section of the 

 of an inch ', they are of an Femur, or leg-hone of an Ostrich 



oval figure, and somewhat flat- 

 tened on their opposite sur- 

 faces, and are usually about 

 one- third greater in thickness 

 than they are in breadth ; hence, as wdll be presently 

 shown, it becomes necessary to know in what direction 

 a specimen is cut, in order to judge of their comparative 

 size. The older anatomists supposed them, from their 

 opacity, to be little solid masses of bone ; but if the sec- 

 tion be treated with spirits of turpentine coloured with 

 alkanet-root, or if it has been soaked in very liquid 

 Canada balsam for any great length of time, it can 

 then be unequivocally demonstrated that both thes® sub- 

 stances will gain entrance into the bone-cells through the 

 canaliculi. The bone cells, when viewed by transmitted 

 light, for the most part appear perfectly opaque ; and they 

 will appear the more opaque the nearer the section of 



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(maguified 95 diameters). Wheu 

 contrasted with the preceding 

 figure, it will be noticed that the 

 Haversian canals are much smaller 

 and more numerous, and many of 

 them run in a transverse direction. 



