Ixxxiv HYALINE CARTILAGE. 



the cartilages of the larynx and windpipe, except the epiglottis and corni- 

 cula laryngis, and to the cartilages of the nose. With the exception of the 

 last, these resemble the rib-cartilages also in their tendency to ossify. 



The characters of the temporary cartilages, which are hyaline, will be 

 given in the account of the formation of bone. 



No nerves have been traced into any of the cartilages, and they are known 

 to be destitute of sensibility. 



In the healthy state, 110 blood-vessels penetrate the articular cartilages. 

 Whatever nutrient fluid they require seems to be derived from the vessels of 

 adjoining textures, especially the bone, and to be conveyed through the 

 tissue by imbibition. In the embryo, a layer of vessels is prolonged some 

 way over the surface, underneath the sy no vial membrane ; but, as deve- 

 lopment proceeds, these subsynovial vessels retire towards the circumference 

 of the cartilage, and eventually form a narrow vascular border round it, 

 which has been named the circulus articuli vasculosus. 



When the tissue exists in thicker masses, as in the cartilages of the ribs, 

 canals are here and there excavated in its substance, along which vessels are 

 conducted to supply nourishment to the parts too distant to receive it from 

 the vessels of the perichondrium. But these canals are few and wide apart, 

 and the vessels do not pass beyond them to ramify in the intermediate 

 mass, which is accordingly quite extravascular. It must be further 

 remembered respecting these vascular canals, that many of them lead to 

 spots where the cartilage is undergoing ossification, and convey vessels to 

 supply the bony deposits. 



Ordinary permanent hyaline cartilage contains about three-fifths of its 

 weight of water, and becomes transparent by drying. By boiling it iu 

 water for fifteen or twenty hours, it is resolved into chondrin. This is a 

 substance said to gelatinise on cooling, although it may be doubted whether 

 the congelation is not in reality owing to an admixture of gelatin derived 

 from fibrous tissue not duly separated from the cartilage. Like gelatine, 

 chondrin is thrown down from its solutions by taunic acid, alcohol, ether, 

 creasote, and corrosive sublimate, and not by prussiate of potash. It differs 

 from gelatin in being precipitated by the mineral and other acids, the 

 acetic not excepted ; also by alum, sulphate of alumina, persulphate of iron, 

 and acetate of lead ; the precipitates being soluble in an excess of the 

 respective precipitants. The temporary cartilages are resolved into a matter 

 which has the chemical reactions of chondrin, but does not gelatinise. 

 Cartilage affords by incineration a certain amount of mineral ingredients ; 

 3 '4 per cent, of ashes were obtained from costal cartilages by Frommherz 

 and Gugert, and 100 parts of these ashes were found to consist of 



Carbonate of soda 35*07 



Sulphate of soda ......... 24'24 



Chloride of sodium . . . . . . . . 8'23 



Phosphate of soda . . . . . . . . . 0'92 



Sulphate of potash . . . . . . . .1-20 



Carbonate of lime 18-37 



Phosphate of lime . . . . . . . .4-06 



Phosphate of magnesia ........ 6'91 



Oxide of iron, and loss . . . . . . .1*00 



Von Bibra found the amount of carbonates very small, and that of the 

 other salts very variable. Soda-salts greatly preponderate over those of 

 potash, which may even be absent altogether. 



