THE NATIVE ALBUMINS. 49 



chitosamin on hydrolytic decomposition. Landwehr's animal gum, 

 which has figured very largely as a decomposition product of this 

 order in the older text-books, is probably no unity; on decomposi- 

 tion with strong mineral acids it yields laBvulinic acid, leucin, tyro- 

 sin, and other bodies of this order. 



The amount of reducing substance which can be split off from 

 some of the mucins and mucoids is quite considerable. Ovimucoid 

 thus yields about 30 per cent., submaxillary mucin 34 per cent., the 

 mucin derived from the respiratory tract 34 per cent., and the 

 pseudomucin of ovarian cysts 30 per cent. From the mucoid of 

 sepia eggs v. Furth obtained 36-39 per cent. 



As a class the gluco-albumins contain much less carbon and 

 nitrogen, but more oxygen, than the common albumins, which is 

 accounted for by the large amount of carbohydrate present. 1 



According to Levene, the mucins all contain the chondroitin- 

 sulphuric acid complex, which was formerly supposed to be pecu- 

 liar to chondromucoid. Chondroitin-sulphuric acid is a conju- 

 gate sulphate, and on boiling with dilute hydrochloric acid is 

 decomposed into sulphuric acid and chondroitiri. The latter further 

 yields acetic acid and chondrosin, which in turn supposedly gives 

 rise to glucosamin and glucuronic acid (Schmiedeberg). This, how- 

 ever, has been disproved. Neuberg has shown that neither glucos- 

 amin nor glucuronic acid results on hydrolysis, but a tetra-oxy- 

 amino-capronic acid and a carbohydrate-like substance of unknown 

 character. These decompositions can be expressed by the equa- 

 tions : 



(1) C 18 H 27 N0 14 .S0 3 + H 2 = C 18 H. 27 NO U + H^O, 



Chondroitin-sul- Chondroitin. 



phuric acid. 



(2) C 18 H 27 NO U + 3H 2 = C 12 H 21 NO U + 3CH 3 .COOH 

 -Chondroitin. Chondrosin. Acetic acid. 



(3) C 12 H 21 NO U + *H 2 = C 6 H 13 N0 6 +* 



Chondrosin, Tetraoxy-amido-capronic 



acid. 



The mucins and mucoids are soluble with great difficulty in 

 water and dilute saline solutions, and are insoluble in dilute acids. 

 They possess markedly acid properties and dissolve in dilute alka- 

 lies with a neutral or feebly acid reaction. All mucinous solutions 

 are more or less viscid and extremely difficult to filter. 



The solutions do not coagulate on boiling, but on acidifying with 

 acetic acid they are precipitated, the precipitate being insoluble in 

 an excess of the acid. This precipitation by acids only occurs if 

 sodium chloride or other neutral salts are absent or present only in 



1 Some of the analytical results which have been obtained are the following : 



Carbon. Hydrogen. Nitrogen. 



Mucoid of sepia eggs 49.7 6.96 10.75 



Pseudomucin (from ovarian cysts) . . . 49.7 6.90 10.28 



Mucin of frog's eggs 52.7 7.10 9.30 



4 



