ELEMENTS OF HISTOLOGY. [Chap. vii. 



Robin. They are derived by overgrowth from ordinary 

 marrow cells, and are of importance for the absorption 

 and formation of bone (see below). According to 

 Heitzmann, Malassez, and others, they also have to 

 do with the formation of blood-vessels and blood- 

 corpuscles. 



64. The matrix of osseous substance is dense 

 fibrous connective tissue, i.e., a tissue yielding gelatin 

 on boiling. The cement substance between the fibrils 

 is petrified, owing to a deposit of insoluble inorganic 

 lime salts, chiefly carbonates and phosphates. These 

 can be dissolved out by strong acids (hydrochloric) 

 and are thereby converted into soluble salts. Thus 

 the organic matrix of osseous substance called ossein 

 may be obtained as a soft flexible material, easily 

 cut. 



The bone substance is in the adult state generally 

 lamellated, the lamellae being of microscopic thinness. 



Between every two 

 lamellae are num- 



bers of isolated, 

 flattened, oblong 

 spaces the bone 

 lacuna (Fig. 33), 

 which anastomose 

 by numerous fine 

 canals with one 

 another, and also 

 with those of the 

 next lamella above 

 and below. The 

 appearances are 



very similar to those presented by the lacunae and 

 canaliculi containing the corneal corpuscles, as des- 

 cribed in Chapter Y. 



These bone lacunae and their canaliculi are the lymph- 

 canalicular system of osseous substance, for they are 



m 



nched 



Fig. 33. Osseous Lamellae ; oblo _ 

 bone-lacunae and canaliculi between them. 

 (Atlas.) 



