84 CHONDRIN. 



and other metallic salts (of Ag and Cu), which yield no precipitate 

 with gelatin, while on the other hand mercuric chloride and tan- 

 nin do not precipitate chondrin but are characteristic precipitants 

 of gelatin (see above). Choudrin is powerfully laevorotatory ; in 

 faintly alkaline solution (a) D = - 213'5 ; in presence of excess of 

 alkali this becomes (a) D = - 55'20. : 



By prolonged treatment with boiling water, or shorter heating 

 with dilute (1 p.c.) sulphuric acid or stronger hydrochloric acid, 

 chondrin is decomposed with the formation of a nitrogenous crys- 

 tallisable product which characteristically reduces alkaline solu- 

 tions of cupric oxide. 2 Opinions however differ considerably as to 

 the real nature of this reducing substance. It was at one time 

 regarded as a true carbohydrate, and more recently Landwehr has 

 identified it with his animal-gum. 3 (See above sub mucin.) There 

 is now but little doubt that it contains nitrogen, is possessed of 

 distinct acid properties, and exhibits marked carbohydrate affini- 

 ties apart from its reducing powers. 4 According to the older and 

 some recent observers its solutions are laevorotatory, 5 but v. Mer- 

 ing states that it is dextrorotatory. 6 Its real nature cannot be 

 regarded as yet as definitely established. When the action of the 

 boiling acids is prolonged, or if caustic alkalis or barium hydrate 

 is employed, chondrin undergoes a further profound decomposition 

 resulting in the formation of a large number of crystalline pro- 

 ducts ; with regard to these the fact of chief importance and 

 interest is the general presence among them of leucin, and the 

 entire absence of tyrosin and glycin (glycocoll), and the occurrence 

 of aspartic and glutamic acids in very minute traces only, if at all. 7 



We have so far spoken of chondrin as a distinct and individual sub- 

 stance; the view has however been put forward that it is in reality 

 merely a mixture of mucin and gelatin, 8 and the outcome of more re- 

 cent work seems to be tending towards the strengthening of this view. 9 

 When hyaline cartilage is extracted with baryta water or dilute alkalis 

 a solution is obtained which yields reactions typical of the so-called 

 chondrin and closely resembling those characteristic of mucin; the 

 undissolved residue when boiled with water is dissolved into a solution 

 which gives the reactions in general typical of gelatin. Morner, 

 treating sections of hyaline cartilage in succession with dilute hydro- 

 chloric acid (! -2 p.c.) and caustic potash (*1 p.c.), finds that 

 rounded masses of the matrix are dissolved out and leave thin a resid- 



1 de Bary, loc. cit. (sub gelatin). 



2 v. Mering, Inaug.-Diss. Strassburg, 1873. 



3 Pfliiger's Arch. Bd. xxxix (1886), S. 198. 



4 Krukenberg, Zt. f. Bid. Bd. xx. (1884), S. 307. Morner (Swedish). See abst. 

 in Maly's Bericht. 1887, S. 308, 1888, S. 217. 



5 Petri, Ber. d. deutsch. chem. Gesell. Jahrg xn. (1879), S. 267. 



6 See Hoppe-Seyler's Hdbch. d. physiol.-path chem. Anal. (5 Auf. 1883), S. 301. 



7 Schiitzenberger et Bourgeois, cit. (sub gelatin). 



8 Morochowetz, Verhand. d. naturhist.-med. Ver. Heidelbg. Bd. i. (1876), Hft. 5. 



9 Krukenberg, Morner, loc. cit. 



