292 THE SOLIDS. 



nature wholly distinct from those of ordinary cellular tissue, 

 and which have their origin in cells ; under no circumstance 

 can either cells or nuclei be discovered in the fibres of carti- 

 lages. 



Cartilage is not capable of regeneration: when it has 

 been fractured, the union of the surfaces is very incom- 

 plete, and principally by means of cellular tissue. 



The formation of cartilage almost invariably precedes the 

 development of bone, of which we shall shortly have to 

 speak more particularly in the Chapter on Bone. 



Masses of cartilage are also occasionally produced upon 

 the external surface of the syno vial membrane of joints ; these 

 are at first peduncated, but at length cease to have any con- 

 nexion with the organization, and move freely about in 

 the cavity of the joints. 



Occasionally, though rarely, cartilage is developed in the 

 cellular tissue of glands, forming a solid tumour, which was 

 first described by Miiller under the name of Enchondroma, 

 and of which I recently had the pleasure of receiving a very 

 excellent example from Dr. Letheby. 



USES OF CARTILAGES. 



The uses of cartilages are of a mechanical nature, depend- 

 ing upon certain physical properties. 



Thus we find them to be situated in localities, where 

 solidity is required in combination with flexibility and 

 elasticity. 



In the larynx, the flexibility and elasticity of cartilages 

 assists in the modulation of the voice. 



In the nose, so liable to injury, their flexibility often 

 allows this organ to sustain severe blows without detriment. 



The articular cartilages protect the bones from injury to 

 which they would be otherwise so subject in the sudden and 

 violent exertions of the body, as in jumping on account of 

 their solid and unyielding nature. 



