CHAPTER IX. 

 TISSUES OF THE CONNECTIVE SUBSTANCE. 



I. THE CONNECTIVE TISSUES. 



THE form-elements of the typical connective tissues are cells of 

 various kinds, of a not very well-known chemical composition, and 

 gelatin-yielding fibrils, which, like the cells, are imbedded in an interstitial 

 or intercellular substance. The fibrils consist of collagen, the interstitial 

 substance contains chiefly mucoid (tendon-mucoid) , besides ser globulin 

 and seralbumin, which occur in the parenchymatous fluid (LoEBiscn 1 ). 



The connective tissue also often contains fibers or formations con- 

 sisting of elastin, sometimes in such great quantities that the connective 

 tissue is transformed into elastic tissue. A third variety of fibers, the 

 reticular fibers, also occurs, and according to SIEGFRIED these consist 

 of reticulin. 



If finely divided tendons are extracted in cold water or NaCl solu- 

 tions, the protein bodies soluble in the nutritive fluid in addition to a 

 little mucoid are dissolved. If the residue is extracted with half- 

 saturated lime-water, then the mucoid is dissolved and may be precipi- 

 tated from the filtered extract by adding an excess of acetic acid. The 

 extracted residue contains the fibrils of the connective tissue together 

 with the cells and the elastic substance. 



The so-called tendon mucin is not true mucin, but a mucoid, which, 

 as first shown by LEVENE and then by CUTTER and GIES, contains a 

 part of its sulphur as an acid related to chondroitin-sulphuric acid. 

 These mucoids, which, according to CUTTER and GIES, are mixtures* of 

 several glycoproteins, contain 2.2-2.33 per cent sulphur, as shown by 

 the analyses of CHITTENDEN and GIES, as well as those of CUTTER and 

 GIES. The quantity of sulphur split off as sulphuric acid was 1.33-1.62 

 per cent (CUTTER and GIES) . VAN LIER 2 has prepared a substance at least 

 closely related to tendon mucoid from the hard skin of man and certain 

 animals. This mucoid yielded an ethereal sulphuric acid, a glucothionic 

 acid with 1.58-3.03 per cent sulphur in the barium salt, and was variable 

 in different animals. It gives the orcin reaction for glucuronic acid. 



1 Zeitschr. f. physiol. Chem., 10. 



2 Levene, ibid., 31 and 39; Cutter and Gies, Ainer. Journ. of Physiol., 6; Chitten- 

 den and Gies, Journ. of Exp. Med., 1; van Lier, Zeitschr. f. physiol. Chem. 61. 



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