CORNEA. 525 



extent in all matrices, and of these it is richest in the cartilage. Ten- 

 dons, ligament-urn nuchae, and cartilage of the ox contained 0.06, 0.07, 

 and 2.17 p. m. glycogen respectively (HANDEL). 



HOPPE-SEYLER found in fresh human rib-cartilage 676.7 p. m. water, 

 301.3 p. m. organic and 22 p. m. inorganic substance, and in the cartilage 

 of the knee-joint 735.9 p. m. water, 248.7 p. m. organic and 15.4 p. m. 

 inorganic substance. PICKARDT found 402-574 p. m. water and 72.86 

 p. m. ash (no iron) in the laryngeal cartilage of oxen. The ash of car- 

 tilage contains considerable amounts (even 800 p. m.) of alkali sulphate, 

 which probably does not exist originally as such, but is produced in great 

 part by the incineration of the chondroi tin-sulphuric acid and the chon- 

 dromucoid. The analyses of the ash of cartilage therefore cannot give 

 a correct idea of the quantity of mineral bodies existing in this substance. 

 The cartilage is richest in sodium of all the tissues of the body, and accord- 

 ing to BUNGE l the amount of Na and Cl is greatest in young animals. 

 In 1000 parts of cartilage dried at 120 C., BUNGE found 91.26 parts 

 NaoO in the shark, 33.98 in the ox embryo, 32.45 in a fourteen-day-old 

 calf, and 26.4 in a ten-weeks-old calf. 



Ochronose is the brown to black coloration of the cartilage which 

 sometimes occurs and which has also been observed in several cases of 

 alcaptonuria (see Chapter XV). The nature of these melanine-like 

 pigments is unknown. 



The Cornea. The corneal tissue, which, in a chemical sense, is con- 

 sidered by many investigators to be related to cartilage, contains traces of 

 proteid and a collagen as chief constituent, which C. MORNER 2 claims 

 contains 16.95 per cent N. According to him it also contains a mucoid 

 which has the composition C 50.16, H 6.97, N 12.79, and S 2.07 per 

 cent. On boiling with dilute mineral acid this mucoid yields a reducing 

 substance. The globulins found by other investigators in the cornea 

 are not derived from the matrix, according to MORNER, but from the layer 

 of epithelium. MORNER believes that DESCEMET'S membrane consists 

 of membranin (page 167), which contains 14.77 per cent N and 0.90 

 per cent S. 



In the cornea of oxen His 3 found 758.3 p. m. water, 203.8 p. m. 

 gelatin-forming substance, 28.4 p. m. other organic substance, besides 

 8.1 p. m. soluble and 1.1 p. m. insoluble salts. 



1 Hoppe-Seyler, cited from Kiihne's Lehrbuch d. physiol. Chem., 387; Pickardt, 

 Centralbl. f. Physiol., 6, 735; Bunge, Zeitschr. f. physiol. Chem., 28. 



2 Zeitschr. f. physiol. Chem., 18. 



3 Cited from Gamgee, Physiol. Chem., 1880, 451. 



