SECT. 91 •] OSSEOUS SYSTEM. 171 



pale granules, of o , ooo2'" in size. If water, or a weak solution of 

 sugar or albumen, be added to a section, two layers, as it were, 

 appear, in man}' cases, in eacli lamella, one pale and more homo- 

 geneous, the other darker granulated, and generally also striated. 

 In sections parallel to the surface, the bone, in many places, 

 appears almost entirely homogeneous, without any trace of a 

 granular structure; in others, an indistinct granular aspect, or 

 small points (Deutsch), are exhibited, and with a longitudinal 

 striation, which is referred by Sharpey to reticularly united fibrils. 

 Frequently there is also exhibited, in the cartilage of the decalci- 

 fied compact substance, a coarse fibrous appearance, which arises, 

 perhaps, from the fibrous bundles of the former blastema. If 

 bones be calcined and the fragments crushed, small angular gra- 

 nules, according to Tomes, come to view. They are, according to 

 Tomes, Ard to £th of the diameter of human blood-corpuscles; 



according to Todd and Bowman, -g-oVo" *° TToWo"> au & are a l so 

 obtained by boiling bones in a Papin's digester. From this, and 

 from the granular appearance of fresh bones, to which also Tomes 

 and Todd and Bowman call attention; further, from the nearly 

 equal size of the granules seen here with those demonstrated 

 by Tomes ; and lastly, from the circumstance that bones, when 

 treated with hydrochloric acid and when calcined, exhibit in both 

 cases a similarly continuous substance without interstitial vacuities, 

 it may be assumed that the osseous tissue, in mammalia and man, 

 consists of an intimate mixture of organic and inorganic com- 

 pounds, in the form of firmly united fine granules ; although we do 

 not by this mean to deny that perfectly homogeneous osseous tissue 

 may be found in the lower animals, and in certain places in the 

 higher (see Tomes and De Morgan, I.e., pp. 13, 14). 



§ 91. Lacuna; and Canaliculi. — Scattered through the whole 

 osseous substance and in all the lamella?, there are seen, in dry 

 sections, microscopic corpuscles of the form of cucumber seeds, 

 with many fine branched and, in part, anastomosing rays. These 

 corpuscles are dark by transmitted, and white by reflected light, 

 which is owing, not to a deposit within them of calcareous 

 salts, as was formerly believed, whence they were called bone- 

 corpuscles, or calcigerous corpuscles, but simply to their being 

 filled with air. In fresh bones, there exists in every lacuna a 

 delicate-walled cell, completely filling it, with clear contents and a 

 single nucleus. This included cell sends out many fine processes 

 into the canaliculi, and is connected with similar processes of 



