146 DIGESTION OF MUCIN AND ELASTIN. [BOOK II. 



3. Digestion of Mucin. 



We possess few observations on the digestion of Mucin. 



By prolonged boiling of a feebly alkaline solution of mucin, Eichwald 

 obtained a body which he denominated mucin-peptone, which possessed 

 essentially the characters of the peptones of the albuminous substances 

 proper. 



According to Kiihne and Schiff it is not attacked by the con- 

 stituents of the gastric juice. It would nevertheless appear probable 

 that by the prolonged action of pepsin and hydrochloric acid, mucin 

 undergoes some decomposition. The subject requires investigating 

 anew. 



4>. Digestion of Elastin. 



Etzinger 1 shewed that elastin when subjected to digestion for 

 several days with pepsin and hydrochloric acid is dissolved. The 

 Author finds that the solution of elastin, purified as perfectly as 

 possible, is complete. 



Horbaczewski 2 and Morochowetz 3 studied the products obtained 

 by the action of artificial gastric juice upon elastin, the former 

 observer extending his observations by studying the action of 

 human gastric juice, the product of a gastric fistula, upon that 

 substance. 



Horbaczewski described two products of the action of artificial 

 gastric juice upon elastin, to which he gave the name of hemi- 

 elastin and elastin-peptone. 



Chittenden and Hart 4 have made a still more elaborate investi- 



tation which has led them to the conclusion that, under the in- 

 uence of pepsin and hydrochloric acid, there are formed two 

 bodies, both belonging to the class of albumoses, and not to that of 

 true peptones, inasmuch as they are precipitable by ammonium 

 sulphate. To the first of these bodies, which corresponds to Hor- 

 baczewski's hemi-elastin, they give the name proto-elastose ; this 

 body is precipitated by NaCl. To the second, corresponding to 

 Horbaczewski's elastin-peptone, they assign the name deutero- 

 elastose. Both these bodies exhibit the biuret reaction. 



The ultimate analyses of proto-elastose do not differ materially 

 from those of the elastin which yielded it. On the other hand, the 

 results of the analyses of elastin and deutero-elastose are not so 

 concordant. These analyses do not, however, throw any special 

 light upon the relations between the bodies. 



1 Etzinger, loc. cit. 



2 Horbaczewski, ' Ueber das Verhalten des Elastins bei der Pepsin verdauung,' 

 Zeitschrift f. physiol. Chemie, Vol. vi. p. 330. 



3 Morochowetz, ' Verdauungsgesetze.' Maly's Jahresbericht (1886), p. 271. 



4 B. H. Chittenden and A. S. Hart, ' Elastin und Elastosen.' Ze.itschriftf. Biolog., 

 Vol. xxv. (1889), p. 368. 



