CONNECTIVE TISSUE IN MUSCLE. 



423 



very large excess of acid ; on treatment with boiling alcohol, 

 nearly all of it went into solution as fatty acid, leaving only a 

 trace of proteid behind. Portions of fatty acid obtained in 

 this way melted above 62 C. 



In order to determine the identity of preparation A as 

 mucin, portions of about 1.5 grams were heated for fourteen 

 hours with two per cent hydrochloric acid. It was hoped to 

 bring about a cleavage of the glycoproteid in this way, if 

 mucia were present.* The solution was nearly neutralized 

 (never becoming alkaline), and was concentrated to a small 

 volume. The presence of a soluble carbohydrate was tested 

 for with Fehling's solution. No reduction was ever observed, 

 and no carbohydrate group could be detected in any preparation 

 of the so-called mucin. Furthermore, the mucins are all char- 

 acterized by a relatively low content of nitrogen in contrast 

 with simple proteids. Thus tendon mucin contains less than 

 12 per cent of N, while snail mucin and submaxillary mucin 

 contain 13.6 and 12.3 per cent respectively.! Analyses of the 

 preparations from muscle gave far higher results, as will be 

 seen in the summary below. The nitrogen determinations 

 were made in duplicate by the Kjeldahl-Gunning method. The 

 ANALYSES OF PREPARATION A. 



figures given are calculated for the ash-free substance. Since 

 the nucleoproteids resemble the true mucins in their solubili- 

 ties, phosphorus determinations were made by Hammarsten's 

 method, in order to ascertain whether the material under inves- 

 tigation belonged to the former class. Only traces of phos- 

 phorusless than 0.01 percent were found, and these were 

 evidently due to adherent phosphate also detected in the ash. 



* Chittenden and Gies, Journal of Experimental Medicine, 1896, i, p. 186. 



t Halliburton, Schaefer's Textbook of Physiology, 1898, i, p. 62. 



