1 1 4 THE CHEMISTR Y OF THE TISSUES AND ORGANS. 



great bulk of the organic solids is derived from the matrix of the 

 cartilage. 



In fibrocartilage, the hyaline matrix is pervaded either by white 

 fibres (white fibrocartilage), or by yellow fibres (yellow or elastic fibro- 

 cartilage). 



In contrast with true bone, the analysis (by Fremy) of the calcified 

 cartilage of the ray may be here given : 



Ash per cent. . . . 30*00 

 Calcium phosphate . .27*7 



Calcium carbonate . . 4'3 

 Magnesium phosphate, traces. 



The matrix of hyaline cartilage. The organic basis of the matrix was 

 formerly described as choinlriijcn ; ^nd just as gelatin is obtained from 

 collagen on boiling, so chondrin is obtained by boiling chondrigen. 

 Chondrin, like gelatin, gelatinises on cooling a solution of it made with 

 warm water, but in many of its reactions it differs from gelatin. 



Elementary analyses of chondrin, however, showed very great dis- 

 crepancies, and Morochowetz 1 arrived at the conclusion that chondrin is 

 not a chemical unit but a mixture of gelatin and mucin. This conclusion 

 has been more recently amplified by C. T. Morner, 2 who worked under 

 the superintendence of Hammarsten. 



The matrix contains four substances (1) collagen, (2) an albuminoid, 

 (3) chondromucoid, and (4) chondroi tin-sulphuric acid. Of these con- 

 stituents the last two, with perhaps a little collagen, lie around the cells, 

 forming what Morner calls chondrin balls; they correspond to the mucin 

 of Morochowetz, or hyalogen of Krukenberg, and are coloured blue by 

 methyl-violet. They lie in the meshes of a network composed of collagen 

 and inucoid, which is stainable by tropseolin. 



These four constituents may be separated as follows. The mucoid 

 and chondroitin-sulphuric acid are dissolved out with 0'2 to 0*5 per 

 cent, solution of potash ; the collagen is dissolved out by hot water, being 

 converted into gelatin in the process; the albuminoid remains undissolved. 



(1) The collagen differs from ordinary collagen in only containing 

 164 per cent, of nitrogen. 



(2) The albuminoid, which is found only in late adult life, is a proteid- 

 like substance of an insoluble nature. It contains loosely combined 

 sulphur. It differs from elastin in its high percentage of sulphur (see p. 73). 



(3) Chondromucoid. This substance has the following percentage 

 composition : C, 47'3 ; H, 642; N, 12-58; S, 242; 0, 31-28 (Morner). 

 The sulphur is loosely combined. Chondromucoid gives the ordinary 

 proteid reactions. On decomposition, it yields the usual decomposition 

 products of proteids, with chondroitin-sulphuric acid in addition; this 

 latter substance is, on further decomposition, broken up into sulphuric 

 acid and a reducing substance. Schmiedeberg 3 regards chondromucoid 

 as a union of proteid with chondroitin-sulphuric acid. 



(4) Chondroitin-sulphuric acid. This substance was called chondroitic 

 acid by Bodeker 4 and Krukenberg 5 (who classed it among his hyalins, 



1 Verliandl. d. natur'h.-mcd. Ver. zu Heidelberg, Part 5, Bd. i. 



2 Ztschr. f. pliysiol. Chem., Strassburg, Bd. xii. S. 396; Skandin. Arch. f. PhysioL, 

 Leipzig, Bd. i. S. 210. 



3 Arch. f. exper. Path. u. PharmakoL, Leipzig, 1891, Bd. xxviii. S. 355. 



4 Ann. d. Chem., Leipzig, 1861, Bd. cxvii. S. 111. 



5 Ztschr. f. BioL, Munchen, Bd. xx. S. 307. 



