STRUCTURE AND PHYSIOLOGY OF ANIMALS 



25 



occur together in spaces scattered through the matrix : sometimes 

 condensation of the matrix round each of the spaces in which the 

 cells are contained forms a cell-capsule. The outer surface is 

 covered over by a fibrous membrane the perichondriu/n. Carti- 



2. Fatty tissue ; F, fat cells ; B, connective-tissue fibrils. (From Lang, after Ranvier.) 



lage is frequently hardened by the deposition in the matrix of salts 

 of lime and is then known as calcified cartilage. 



In bone or osseous connective tissue (Fig. 15) the matrix is exceed- 

 ingly dense and hard owing to its being strongly impregnated with 

 carbonate and phosphate of lime. It consists of numerous thin 

 plates or lamella?, which are arranged partly parallel with the sur- 

 face, partly concentrically around certain canals (c) the Haccrsian 



Fie. 13. Hyaline cartilage. 



Fit:. 14. Fibm-ca; ' 



canals in which blood vessels lie. The cells, or lonc^corpuscks, lie 

 in minute spaces the lacunoe between the lamella 3 , and a system 

 of exceedingly fine channeTs^-the c<matoite extend from lacuna 

 to lacuna, containing fine protoplasmic processes by means of which 

 neighbouring cells are placed in communication with one another. 

 The outer surface of the bone is covered by a vascular fibrous 



