60 PRACTICAL MICROSCOPY. 



channels, and a nerve filament. The whole is supported by connective- 

 tissue cells with delicate processes. The walls of the lymph spaces are 

 prolonged into the caualiculi and thus placed in connection with the 

 elements of the surrounding lacunae. 



FIG. 45. DIAGRAM OF AN HAVERSIAN CANAL. 



A. Artery. 



B. Vein. 



C. Nerve. 



D. D, D. Lymph-channels. 



Each lacuna contains a bone corpuscle, the protoplasmic body of 

 which sends prolongations into the contiguous canaliculi. In the adult 

 bone, the cell is shrunken ; and the processes just mentioned are not 

 readily demonstrable. 



FIG. 46. - DIAGRAM OF A BONE LACUNA. 



A, A. Ground-substance of the bone. 



B, B. Limiting membrane of the bone corpuscle within the lacuna. 



C, Nucleus and nucleolus of the corpuscle. 



D, D. Projection of the cell-body into the canaliculi. 



" 



Fig. 44 has been drawn from a section of dry bone which has been 

 sawn as thin as possible, and afterward rubbed down on a hone with 

 water. It is a tedious process, and shows little but the osseous ma- 

 trix. Bone should be decalcified for microscopical work, and it may 



