Chip, vi.] CARTILAGE. 45 



a network of branched cells ; but in the adult state 

 the reticulum itself possesses no nuclei. Those found 

 on it do not form an essential part of it. 



(2) The neuroglia of Virchow is a dense network 

 of very fine homogeneous fibrils which form the sup- 

 porting tissue for the nervous elements in the central 

 nervous system. These fibrils are supposed to be 

 elastic fibres (Gerlach). Embedded in the network of 

 these fibres are found branched nucleated flattened 

 cell plates, which are the proper connective tissue cells. 



(3) Gelatinous tissue. This occurs chiefly in 

 the embryo, being the unripe state of fibrous 

 connective tissue. It consists of spindle-shaped or 

 branched connective tissue cells, separated from one 

 another by a homogeneous transparent mucoid sub- 

 stance. It is met with in the umbilical cord and in 

 the cavity of the middle ear of the embryo, and in 

 the places where fibrous connective tissue is to be 

 developed. After birth it is found in the tissue of 

 the pulp of the teeth, and in some places as precursor 

 of fat tissue. 



CHAPTER VI. 



CARTILAGE. 



54. Cartilage consists of a firm ground substance 

 which yields cliondrin, and of cells embedded in it. 

 Most cartilages (except on the articulating surface) 

 are covered on their free surface with a membrane 

 of fibrous connective tissue with a few elastic fibrils. 

 This membrane is supplied with blood-vessels, lym- 

 phatics, and nerves, and is of essential importance for 

 the life and growth of the cartilage. This is the peri- 

 cJwndrium. There are three varieties of cartilage. 



