THE OSSEOUS SYSTEM. 331 



force. At an earlier age, when the cartilage is in greater relative 

 proportion, the hardness of the bones is much less, their sus- 

 taining power consequently less considerable, and they are 

 more liable to be bent; whilst on the other hand, owing to 

 their greater elasticity, they are much less liable to be broken. 

 This is the case in a much higher degree in rachitis, in which 

 morbid condition, the organic constituents amount to from 

 70 to 80 per cent. A condition the reverse of this is 

 observed in old age, when the bones, though certainly harder, 

 are more brittle, and therefore more readily fractured, to 

 which liability, however, the rarefaction of the tissue which 

 takes place in consequence of age, partly contributes. The 

 inflammability of bone depends upon its organic basis, and its 

 capability of resisting putrefaction to the inorganic con- 

 stituents. The latter being so intimately combined with the 

 animal tissues, serve as a protection to them, so that bones from 

 ancient burial places, and those of fossil animals still retain the 

 full proportion of cartilage. 



The true cartilages, even in the foetus, contain, in their 

 organic basis, from 50 to 75 per cent, of water, 3 to 4 per cent, 

 of salts (chiefly of soda and carbonate of lime, and also some 

 phosphate of lime and magnesia). The organic basis, has been 

 hitherto supposed to consist entirely of chondrin, a substance 

 allied to gelatin, soluble in boiling water and gelatinising as 

 it cools; but it was noticed by Brims (p. 216), that the matrix 

 and the cells of cartilage were not equally soluble in water, 

 and Mulder and Dondei's have rendered it probable that the 

 chondrin, which had hitherto been investigated, is not a simple 

 substance, and that the cartilages consist of several bodies of 

 different natures, the matrix, and the membranes of the parent 

 cells, their contents, and the secondary cells, of which the first 

 is move soluble in water, potass, and sulphuric acid, than the 

 others. 



The fibro-cartilages (cartilages containing connective tissue) 

 have been, as yet, but little investigated. J. Miiller, in the 

 interarticular cartilages of the knee of the Sheep, found no 

 chondrin; whilst Donders, on the other hand, met with it in 

 the intervertebral ligaments ('IIoll. Beitr.,' p. 264); he did 

 not determine whether they also contained gelatin. According 

 to Virchow, the gelatinous, nuclear portion of these ligaments, 



