CHAPTER X. 

 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 serglobulin 

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



The connective tissue also often contains fibres or formations con- 

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

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

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

 of reticiilin. 



If finely divided tendons are extracted in cold water or NaCl solutions, 

 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 precipitated 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 miicin, 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 2 ) . 



The fibrils of the connective tissue are elastic and swell slightly in 

 water, somewhat more in dilute alkalies or in acetic acid. On the other 

 hand, they shrink by the action of certain metallic salts, such as ferrous 



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



2 Levene, ibid., 31 and 39; Cutter and Gies, Amer. Journ. of Physiol., 6; Chittenden 

 and Gies, Journ. of Exp. Med., 1. 



519 



