42 CARTILAGE. 



failed in deciding. The inquiry is rendered the more difficult by 

 the circumstance, that the chondrin itself becomes partially 

 changed during the process taken to obtain it; chondrin being 

 converted, like glutin, by boiling into a substance which does not 

 gelatinise, and is soluble in cold water. 



The products of the decomposition of chondrin have also failed 

 in affording us any important results ; we merely know from 

 Hoppe's observations, that chondrin, when decomposed by con- 

 centrated sulphuric acid, yields (in addition to extractive matters) 

 leucine only, and no glycine, but when treated with a concentrated 

 solution of potash, glycine only, and no leucine, besides extractive 

 matters. 



The fibrous matrix of fibro-cartilage must have a totally 

 different composition from that of true cartilage, as we see from 

 the micro-chemical investigations of Bonders and Mulder. After 

 exposing cartilage of this kind (as, for instance, one of the inter- 

 vertebral bodies) for a moderate time to the action of a concen- 

 trated solution of potash, or of sulphuric acid, the fibrous character 

 of the matrix, when observed under the microscope, is found gra- 

 dually to disappear, but these agents fail equally with concentrated 

 acetic acid in actually dissolving it ; for a close examination shows 

 that the individual fibres merely swell and assume a gelatinous 

 appearance, and consequently become less perceptible to the eye. 

 Donders further observed that, in addition to the cartilage-cells, 

 there were fibres situated between these gelatinous bundles, which 

 remained almost wholly unchanged in the sulphuric acid, and bore 

 some resemblance to nuclear fibres, and besides these there were 

 some fibres of connective tissue. The fibro- cartilages dissolve 

 for the most part on boiling, and leave only a deposit of granular 

 nuclei and a few cells. The gelatinising fluid obtained from these 

 cartilages exhibits nearly the same reactions as the chondrin 

 extracted from the intercellular substance of true cartilage. Ac- 

 cording to Donders, this solution yields only a slight precipitate 

 with tannic acid, but on the addition of alum yields, like chondrin, 

 a compact deposit, which, however, does not disappear in an 

 excess of the solution. Bichloride of platinum produces a con- 

 siderable precipitate, which is insoluble in an excess of the test. 



The semilunar cartilages of the knee-joint have commonly 

 been reckoned amongst the fibro-cartilages, but J. Mliller showed 

 long since, (in the case of the sheep,) that they yield no chondrin, 

 but glutin only, on boiling. Donders, Kolliker, and other histo- 

 logists, agree in considering that these cartilages, like the inter- 



