CEMENT 289 



are prolonged into the canaliculi (figs. 183-186). The lacu- 

 rial cells are very clearly seen in specimens prepared by the 

 Weil process, which have been previously stained with borax 

 carmine. 



The lacunal cells in bone were first described by Virchow. 

 They entirely fill the lacuna in the fresh state and send 

 processes along the canaliculi. The lacunal cells in cement 

 are identical in essential structure with those of bone, 

 enclosing a large readily stained nucleus with one or two 



FIG. 182. Large overlap of cement, human molar. 

 d. Dentine ; e. enamel ; c. cement. ( x 50. ) 



nucleoli. In several instances the lacuna with its contained 

 cell and processes has been isolated from the bone, the 

 walls of the space having resisted the decalcifying acid, as 

 the Neumann's sheaths do in dentine; and fig. 183, from 

 Schafer's Microscopic Anatomy, shows such a separated 

 lacuna with its contained cell and processes. As this author 

 says, ' It can scarcely be doubted that the protoplasm of 

 the nucleated corpuscle takes an important share in the 

 nutritive process in bone, and very probably serves both 

 to modify the nutritive fluid supplied from the blood and 

 to further its distribution through the lacunar and canali- 



MUMMERY 



