EPITHELIAL AND CONNECTIVE TISSUES. 23! 



Yellow elastic tissue also contains mucoid and collagen but these 

 are present in much smaller amount than in white fibrous tissue, 

 as may be seen from the following percentage composition of 

 the fresh ligamentum nuchce of the ox as determined by Vandegrift 

 and Gies : 



Water 57-57% 



Solids 4243 



Inorganic matter 0.47 



Organic matter 41.96 



Fatty substance (ether-soluble) 1.12 



Coagulable protein 0.62 



Mucoid 0.53 



Elastin 31.67 



Collagen 7- 2 3 



Extractives, etc 0.80 



EXPERIMENTS ON ELASTIN. 



1. Preparation of Elastin (Richards and Gies). Cut the lig- 

 ament into fine strips, run it through a meat chopper and wash 

 the finely divided material in cold, running water for 24-48 hours. 

 Add an excess of half -saturated lime water (see note at bottom 

 of p. 229) and allow the hashed ligament to extract for 48-72 

 hours. Decant the lime-water, remove all traces of alkali by wash- 

 ing in water and then boil in water with repeated renewals until 

 only traces of protein material can be detected in the wash water. 

 Decant the fluid and boil the ligament in 10 per cent acetic acid 

 for a few hours. Treat the pieces with 5 per cent hydrochloric 

 acid at room temperature for a similar period, extract again in hot 

 acetic acid and in cold hydrochloric acid. Wash out traces of acid 

 by means of water and then thoroughly dehydrolyze by boiling al- 

 cohol and boiling ether in turn. Dry in an air-bath and grind to 

 a powder in a mortar. 



2. Solubility. Try the solubility of the finely divided elastin, 

 prepared by yourself or furnished by the instructor, in the ordinary 

 solvents (see page 23). How does its solubility compare with 

 that of collagen? 



3. Millon's Reaction. 



4. Xanthoproteic Reaction. 



5. Biuret Test. 



6. Hopkins-Cole Reaction. Conduct this test according to the 

 modification given on page 101. 



7. Test for Loosely Combined Sulphur. 



