CONNECTIVE TISSUE. 197 



stand how corpuscles imbedded in a dense and tough basis-sub- 

 stance could enlarge and divide cartilaginous tissue itself, 

 moreover, being perhaps the most inactive of all tissues. These 

 multiple bodies cannot be the products of a division, as they are 

 obviously formed simultaneously with the cartilage, and corre- 

 spond to the double or treble, etc., corpuscles so often seen in the 

 territories of other varieties of connective tissue. They cannot 

 alter, unless the dense basis-substance around them is liquefied, 

 or they themselves are transformed into basis-substance. 



Hyaline cartilage is a very common tissue in the body, and 

 is found in an amount varying with the age of the individual. 

 At a certain period of embryonal development, the entire skele- 

 ton is composed of hyaline cartilage, and from this is devel- 

 oped the whole osseous system, with the exception of the flat 

 skull-bones. In the fully developed body this cartilage consti- 

 tutes all articular surfaces of the bones, the anterior portions of 

 the ribs, and the frame of the nose, the larynx r the trachea, and 

 the bronchi. 



The articular cartilage is covered with a single, often indis- 

 tinct, endothelial layer on the gliding surfaces, and surrounded 

 by a richly vascularized delicate fibrous connective tissue the 

 synovial membrane on the lateral surfaces. All other forma- 

 tions of hyaline cartilage are invested by a layer of a dense fibrous 

 connective tissue, the perichondrium, holding numerous blood- 

 vessels, and in its construction more or less identical with that 

 of the periosteum (see page 124). A distinct boundary-line 

 between cartilage and perichondrium does not exist, as a gradual 

 transition of the hyaline into the fibrous basis-substance takes 

 place, and the cartilage corpuscles, which are always flattened 

 near the surface, blend with the oblong or spindle-shaped plas- 

 tids of the fibrous connective tissue. 



Hyaline cartilage is prone to secondary changes. The solid 

 constituents increase with advancing age. According to E. Von 

 Bibra, the ash-remnants of the cartilage of ribs of man continually 

 increase with advancing age to such a degree that, while the 

 solid remnants of a child six months old were only 2.29 per 

 cent., those of a man forty years old were 6.1 per cent. Even in 

 middle age, many of the cartilage-corpuscles contain fat-granules, 

 which often coalesce into fat-globules, replacing to a certain 

 extent the living matter. Granular depositions of lime-salts are 

 often met with in the basis-substance of cartilage of the aged, 

 especially in the ribs and the laryngeal cartilages. Sometimes 



