M2 CHEMISTRY OF THE PROTEIDS CHAP. 



forms a well -defined osazone; 1 whether this substance is gluco- 

 samin has not yet been determined. Tendon-mucoid resists the 

 action of alkalies more strongly than do the mucins. To prepare 

 tendon-mucoid, tendons are extracted with half-saturated lime-water. 

 According to Posner and Gies, 2 tendon-mucoid, in the presence of 

 sulphuric, hydrochloric, or acetic acid, forms relatively stable com- 

 pounds with alkali-albuminates, acid-albumins, proteoses, gelatine, and 

 the water-soluble albumins of muscle, tendon, blood-serum, and egg- 

 white. Tendon-mucoid reacts, therefore, in exactly the same way as 

 would chondro-sulphuric acid and glyco-thioriic acid. These new com- 

 pounds have an acid reaction ; are comparatively insoluble in dilute 

 acids ; behave towards precipitating agents as do mucoids ; do not 

 become coagulated in neutral solutions ; contain more nitrogen than 

 does the mucoid by itself ; and when boiled with dilute hydrochloric 

 acid give rise to glyco-thionic acid and a reducing substance. Because 

 of the ease with which tendon-mucoid reacts with the albuminous 

 substances enumerated above, it is probable that mucoid occurs nor- 

 mally in the body in combinations similar to those obtained in the 

 test-tube. 



Gies 3 has prepared a substance identical with tendon-mucoid from 

 bones, which he calls " osseo-mucoid." It also possesses a high sulphur- 

 content (2 -5 per cent), and contains likewise a paired sulphuric acid, 

 and thus resembles the chondro-mucoid. 



2. Chondro- Mucoid and Chondro- Sulphuric Acid 4 



Johannes Miiller 5 in 1837 called the ground substance of cartilage 

 " chondrin," and believed it to be a special substance ; G. J. Mulder 8 

 in 1838 showed chondrin to contain a definite amount of sulphur. 

 Fischer and Boedeker 7 and de Bary 8 then demonstrated that chondrin, 

 when boiled, gives rise to a reducing substance. Morochowetz 9 

 first recognised that the ground matrix of cartilage is a mixture of 

 ordinary collagen and a mucin-like substance. The full explanation 



1 R. H. Chittenden and W. Gies, Journ. of experiment. Med. 1. 186 (according to 

 Maly'sJahresber.f. Tierchem. 26. 32) (1896). 



2 E. R. Posner and W. J. Gies, Amer. Journ. of PhysioL 11. 404 (1904). 



3 P. B. Hawk and W. J. Gies, Amer. Journ. of Physiol. 5. 387 (1901). 



4 The author has shortened the term chondroitin-sulphuric acid, used in Mandel's 

 translation of Hammarsten's Physiological Chemistry. 



5 Joh. Miiller, Liebig's Annalen, 21. 277 (1837). 



6 G. J. Mulder was the first to make quantitative estimations of the amount of 

 -sulphur and phosphorus in egg-white, fibrin, and serum. 



7 G. Fischer and C. Boedeker, ibid. 117. HI (1861). 



8 J. de Bary, Hoppe-Seyler's Med.-chem. Untersuch. p. 71 (1866). 



9 L. Morochowetz, Verhandl. d. naturhist.-med. Ver. Heidelb. N.F. I. p. 480 (1876). 



