TISSUES OF THE BODY. 185 



A child of six months, . . .2-24 per cent, of ash. 



A child of three years, . . .3*00 



A girl of nineteen years, . . .7*29 



A woman of twenty- five years, . . 3 '92 f , 



A man of twenty years, . . .3-40 



A man of forty years, . . .600 



112. 



The cartilages of the adult body may he regarded as the residue of 

 a tissue very widely distributed through the system at an early period 

 of intra-uterine existence, which has for the greater part given way to the 

 subsequent formation of bone ( 103). In many structures, therefore, 

 this tissue manifests a remarkable degree of transitoriness. And even 

 those cartilages which persist in the body up to its maturity show a 

 certain inclination to undergo anatomical metamorphosis, that of softening, 

 of fibrillation, of calcification, and even of ossification ; in other words, to 

 pass through subsequent processes which in the so-called temporary 

 cartilages had taken place at an earlier epoch ( 106), 



For the rest, cartilaginous tissue, which is, as a rule, non-vascular, 

 possesses but a small amount of transformative power over the matters 

 whicli it receives ; and such as it is, its bearings are unfortunately still 

 very obscure. The nutrition of the tissue occurs in two ways. Some 

 cartilages are clothed with a fibrous membrane, the perichondrium, whose 

 vessels supply the nutritive materials. For all tins it is a strange fact 

 that, in the interior of the cartilage, the tissue appears most highly deve- 

 loped thus at the point most remote from the blood-vessels. How far, 

 and whether indeed the tissue can further grow at all from the perichon- 

 drium, has not yet been ascertained. Other portions of the tissue in 

 question, which enter into the structure of joints, possess no perichon- 

 drium, and depend on the vessels of the adjacent bone for their nutriment. 



According to all this, we have in cartilage to deal with an aggregation 

 of simple cells, whose intercellular substance is its only essential peculi- 

 arity; on which also the physical properties of the tissue, its solidity, 

 hardness, and pliancy, depend. It is owing specially to this latter quality 

 that cartilage is of such importance to the system; it adapts to form sup- 

 ports for other parts, to strengthen the walls of membranous canals, &c., 

 to clothe the ends of bone, forming a layer peculiarly suitable for articula- 

 tions through its hardness, smoothness, and small liability to wear and 

 tear. Finally, it presents itself as a very strong connecting matter for 

 joining bones together. 



Although non-vascular, cartilages may undergo the same changes as 

 other vascular portions of the body, under conditions of inflammatory 

 irritation. Energetic segmentation of its cells has been remarked, as well 

 as increase in size of the capsule and deposit of fats in the body of the 

 cells. The intercellular substance may also split up into fibres and fasci- 

 culi, or break down altogether. Calcification or transformation of the 

 whole into a substance more or less like connective-tissue may also occur 

 (Ned fern, Virchow}. These changes are, in many cases, brought about by 

 but a repetition of the process described in 106. 



The substance of cartilage is not regenerated, however, so that two 

 fractured portions of the latter can only be united again by a connective- 

 tissue cicatrix. But an accidental new formation of cartilage is by no means 

 of rare occurrence. In the first place, it may start from cartilage already 



