566 CHEMISTRY OF THE PROTEIDS CHAP. 



Gelatine from Cartilage. Formerly it used to be supposed that 

 cartilage was composed of a uniform substance which was called 

 chondrigen, and that the latter when boiled gave rise to chondrin or 

 cartilage-glue, but Morochowetz showed that chondrin is a mixture 

 of gelatine and mucin, and Krukenberg confirmed this view. The 

 most exact investigation into the chemistry of cartilage has been made 

 by Morner, according to whom cartilage contains the following 

 substances : 



1 . Chondromucoid and its dissociation-product : 



2. Chondroitin- sulphuric acid. This 'chondro- sulphuric' acid 



occurs normally in cartilage in small quantities. 



3. Collagen. 



4. An albumoid in old but not in young cartilage. 



The framework of old cartilage consists of albumoid + collagen, 

 while the enclosed ' chondrin-balls ' are composed of collagen + mucoid. 

 These two substances have distinct staining reactions and are 

 histologically readily recognisable. 



On treating cartilage with dilute acids at 40 C., a mixture of 

 gelatine + chondro-sulphuric acid is obtained, while boiling in a Papin's 

 pot yields a compound consisting of gelatin + mucoid + chondro-sul- 

 phuric acid. This compound resembles in its reactions the ' chondrin ' 

 of the older observers, and differs from ordinary gelatine in not being 

 precipitated by tannin, because the chondro-sulphuric acid prevents 

 the precipitation of the gelatine moiety. The mucoid is described on 

 p. 542, and the albumoid on p. 577. The glutin of cartilage has been 

 investigated in addition to Morner by Lonnberg, 1 who also examined 

 fish-cartilage, and by Sadikoff. 2 To prepare this gelatine requires 

 very intense boiling with water. The reducing power and the feeble 

 pentose reaction noticed by Sadikoff are probably due to impurities. 



Collagen from Bone or ' Ossein.' The ground substance of bone 

 consists for the greater part of collagen + lime-salts. It contains 

 in addition an albumoid 3 (p. 577), and a mucoid, 4 resembling chondro- 

 mucoid (p. 577). Keratin or other albumins are absent. 5 Bone- 

 gelatine has been investigated by Weiske ; 6 it gives the ordinary 

 gelrtine reactions, and is not readily formed from the collagen. 



1 J. Lonnberg, Holy's Jahresbericht, 19. 325 (1889). 



2 W. S. Sadikoff, Zeitschr. f. physiol. Chem. 39. 411 (1903). 



3 P. B. Hawk and W. J. Gies, Amer. Journ. of Physiol. 7. 340 (1902). 



4 L. Morochowetz, Verhandl. d. Heidelberger naturh.-med. Vereins, N.F. I. p. 480, 

 (1876) ; C. T. Morner, Zeitschr. f. physiol. Chem. 23. 311 (1897) ; P. B. Hawk and 

 W. J. Gies, Amer. Journ. of Physiol. 5. 387 (1901). 



5 H. Smith, Zeitschr. f. Biol. 19. 469 (1883). 



6 H. Weiske, Zeitschr. f. physiol. Chem,. 7. 460 (1883). 



