62 CHEMICAL CONSTITUENTS OF BODY AND FOOD. 



snails. 1 A mucinogen is found in the investment around frogs' eggs ; 2 

 it is also the most important constituent of the intercellular or ground 

 substance of connective tissues, and has been especially investigated 

 in the jelly-like connective tissues (vitreous humour, 3 Whartonian 

 jelly 4 ), and in tendon. 5 



Elementary analysis of different mucins has given different results, as will 

 be seen from the following table : 



The mucins thus contain less carbon, and considerably less nitrogen, 

 than proteids. 



Decomposition products of mucin. By the action of superheated 

 steam, a carbohydrate is split oil' from mucin, which was CM lied animal 

 gum by Landwehr. 11 He assigns to it the formula (C (J H ]0 O ft ). By 

 the action of dilute mineral acids this is converted into a reducing but 

 non-fermentable sugar or giunmose (C G H 1;i O G ). The gum-like substance 

 obtained from submaxillary mucin contains nitrogen. 12 The sugar 

 obtained from tendon mucin by Chittenden yielded an osazone molting 

 at 160, and resembled that obtained from pentoses. F. Miiller 13 has 

 investigated the mucin of sputum. He found it yielded as much as 

 25 to 32 per cent, of a reducing substance ; this is not a pentose, but is 

 probably glucosaniine. 



1 Eichwald, Ann. d. Chcm., Leipzig, 13d. cxxxiv. 



2 Giaeosa, Ztschr. f. physiol. Chcm., Strassburg, 13d. vii. S. 40; Hammarsten, Ar<-/i. /'. 

 d. gcs. Physiol., Bonn, Bd. xxxvi. ; Wolfenden, Journ. Physiol., Cambridge and London, 

 vol. v. p. 91. 



3 R. A. Young, Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 325 ; C. Th. 

 Morner, Ztschr. f. physiol. Chcm., Strassburg. 1893, Bd. xviii. S. 245. References to previous 

 literature will be found in these papers. Young arrived at the conclusion that the principal 

 substance in vitreous humour is mucinogen, not mucin. 



4 Jernstrom, . Jahresb. u. d. Fortschr. d. Thier-Chcm., Wiesbaden, 1889, Bd. x. S. 34. 

 Young, loc. cit., separated two mucins from the Whartonian jelly, one soluble, the other 

 insoluble in excess of acetic acid. 



a Rollett, S'ttsungsb. d. k. Akad. d. Wissciisch., Wien, Bd. xxxix. S. 308, Strieker's 

 "Handbuch," 13d. i. S. 72. Loebisch, Ztschr. f. physiol. Chcm., Strassburg, Bd. x. S. 40 ; 

 Chittenden and Gies, Journ. Expcr. Mcd., Baltimore, 1896, vol. i. p. 188. 



6 Arch. f. d. gcs. Physiol., Bonn, Bd. xxxvi. 7 Loc. cit. 



8 Loc. cit. The high percentage of sulphur found is attributed by Chittenden to proteid 

 impurities. 



9 Ztschr. f. physiol. Chcm., Strassburg, Bd. xii. 



10 Arch. f. d. gcs. Physiol., Bonn, Bd. iv. S. 336. Probably Obolensky's preparation 

 was not so pure as Hammarsten 's. 



11 Ztschr. f. physiol. Chcm., Strassburg, 1881, Bd. viii. S. 124, 199 ; Arch. f. d. <jcs. 

 Physiol., Bonn, Bde. xxxix. and xl. 



12 Hammarsten, " Physiol. Chem.," 3rd German edition, p. 39. 



13 Centralbl.f. Physiol., Leipzig, 1896, Bd. x. S. 480; Sitzungsb. d. Gcscllsch. z. Eeford. 

 d. gcs. Naturw. zu Marburg, 1896, No. 6. 



