520 TISSUES OF THE CONNECTIVE SUBSTANCE. 



sulphate or mercuric chloride, and tannic acid, which form insoluble 

 compounds with the collagen. Among these compounds, which prevent 

 putrefaction of the collagen, that with tannic acid has been found of 

 the greatest technical importance in the preparation of leather. In 

 regard to the collagens, gelatins, elastins, and reticulins, see pages 115 

 to 120. 



The tissues described under the names mucous or gelatinous tissues 

 are characterized more by their physical than by their chemical properties, 

 and have been but little studied. This much, however, is known, that 

 the mucous or gelatinous tissues contain, at least in certain cases, as 

 in the Acalephae, no mucin. 



The umbilical cord is the most accessible material for the investiga- 

 tion of the chemical constituents of the gelatinous tissues. The mucin 

 occurring therein has been described on page 166. C. TH. MORNER J 

 has found a mucoid in the vitreous humor which contains 12.27 per cent 

 nitrogen and 1.19 per cent sulphur. 



Young connective tissue is richer in mucoid than old. HALLIBURTON 2 

 found an average of 7.66 p. m. mucoid in the skin of very young children 

 and only 3.85 p. m. in the skin of adults. In so-called myxoedema, 

 in which a re-formation of the connective tissue of the skin takes place, 

 the quantity of mucoid is also increased. 



The connective tissue and also the elastic tissue are richer in water 

 and poorer in solids in young animals as compared with full-grown 

 animals. This may be seen from the following analyses of the Achilles 

 tendon (BUERGER and GIES) and of the ligamentum nuchae (VAN DE- 

 GRIFT and GIES 3 ) : 



Achilles tendon. Ligament. 



Calf. Ox. Calf. Ox.' 



Water.... 675.1p.m. 628.7p.m. 651.0p.m. 575.7p.m. 



Solids 324.9 " 371.3 



Organic bodies 318.4 366.6 



Inorganic bodies ... 6.1 " 4.7 



Fat 10.4 



Proteid 2.2 



Mucoid 12.83 



Elastin 16.33 



Collagen 315.88 



Extractives, etc 8 . 96 



394.0 ' 424.3 



342.4 " 419.6 ' 



6.6 " 4.7 ' 



11.2 ' 



6.16' 



5.25' 



316.70' 



72.30' 



7.99' 



In regard to the mineral bodies it must be remarked that according 

 to the determinations of H. SCHULZ the connective tissue is rich in silicic 

 acid. The greatest amount was found by him, in the crystalline lens 



1 Zeitschr. f. physiol. Chem., 18, 250. 



2 Mucin in Myxoedema: Further Analyses. King's College Collected Papers No. 1, 

 1893. 



3 Buerger and Gies, Amer. Journ. of Physiol., 6; Vandegrift and Gies, ibid., 5. 



