80 GENERAL ANATOMY OF THE TISSUES. 



medulla being formed in them at the same time. Cartilage possesses no 

 power of regeneration, nor do wounds in cartilage unite by cartilage ; 

 on the other hand, an adventitious development of cartilage is not un- 

 common. 



The different cartilages are : 



a. Cartilage without interstitial substance, or parenchymatous carti- 

 lage. To this belong the chorda dorsalis of the embryo and of many 

 adult fish ; many foetal cartilages ; the cartilages of the gill laminae of 

 fishes in part ; and those of the external ear of many mammalia. 



b. Cartilage with interstitial substance. 



1. With a more homogeneous, chondro-yielding substance : true carti- 

 lage, hyaline cartilage : it is found in the larger cartilages of the respi- 

 ratory organs, those of the articulations, of the ribs, and of the nose ; 

 also in all 8ymphy$e8 and synchondroses immediately in contact with 

 the bones ; in the talus ossis cuboidei, and in the so-called ossifying carti- 

 lages of the foetus. 



2. With a fibrous interstitial substance, yielding no chondrin, or but 

 very little: reticulated cartilage, yellow cartilage, fibro-cartilage in 



Fig. 19. 



i Fig. 20. 



part ; epiglottis, cartilagines Santoriniance, Wrisbergiance, cartilage 

 of the ear and of the Eustachian tube ; ligamenta intervertebralia in 

 part. 



In the Invertebrata many tissues of a similar consistence to cartilage 

 are found, but true cartilage has hitherto been discovered only in the 

 Cuttle-fishes. 



[Cartilage is frequently observed in situations where it does not 

 occur normally. This pathological cartilage resembles morphologically 

 and chemically, the ordinary cartilage, and more especially the variety 

 with an interstitial substance. 



FiG. 19. Portion of the chorda dorsalis of an embryo sheep, 6 lines long: a, sheath ; b, 

 cells, with clear vascular spaces. 



FIG. 20. Cartilage cells from the white layer of the cricoid cartilage: from man magni- 

 fied 350 diameters. 



