CONNECTIVE TISSUES.. 131 



CONNECTIVE TISSUES. 



Besides the areolar tissue which may be the white, 

 fibrous, or the yellow, elastic, there are cartilaginous and 

 osseous tissues. 



WHITE FIBROUS TISSUE. 



Nearly pure white fibrous tissue is found in the ten- 

 dons which are made up of fibers, matrix, and cells. The 

 fibers consist of collagen; the matrix contains mucin; the 

 cells contain proteins and salts. 



288. Chop a tendon finely (the tendon of Achilles 

 can be used) and remove the soluble constituents by wash- 

 ing with cold water. Extract the mucin with lime-water 

 and filter. Preserve the insoluble residue and use the solu- 

 tion for the mucin tests. 



289. Show that mucin gives the biuret and Milton's 

 reactions. 



290. It cannot be coagulated by heating nor does it 

 dissolve in dilute acids (distinction from most other pro- 

 teins) . 



291. It does not reduce Fehling's solution unless it 

 has been boiled for an hour or two with an acid like hydro- 

 chloric. A reducing amido compound is thus prod (iced. 

 When the acid solution is neutralized a precipitate of acid 

 albumin falls. Hence the original mucin contained the 

 reducing substance united with a protein. 



COLLAGEN. 



292. For its preparation use the tendon from which 

 the mucin was removed. Heat the tendon with a little 

 water. On cooling it gelatinizes and gives the gelatin re- 

 actions (page 60). 



