84 CHONDRIN. ELASTIK 



his animal-gum 1 . (See above sub mucin.) There is now but little 

 doubt that it contains nitrogen, is possessed of distinct acid properties 

 and exhibits marked carbohydrate affinities apart from its reducing 

 powers 2 . According to the older and some recent observers its solutions 

 are laevorotatory 3 , but v. Mering states that it is dextrorotatory 4 . 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 crystal- 

 line products; 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 5 . 



We have so far spoken of chondrin as a distinct and individual substance ; the 

 view has however been put forward that it is in reality merely a mixture of mucin 

 and gelatin 6 , and the outcome of more recent work seems to be tending towards 

 the strengthening of this view 7 . 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 hydrochloric acid (! '2 p.c.) and 

 caustic potash (! p.c.), finds that rounded masses of the matrix are dissolved out 

 and leave thus a residual network. The dissolved parts consist largely of a 

 substance (chondromucoid) with marked affinities to mucin, whereas the undissolved 

 network, by treatment with acids or superheated water, is converted largely into 

 typical gelatin. For further details the original papers already quoted should be 

 consulted. 



Elastin. 



This is the characteristic component of the elastic fibres which 

 remain after the removal of gelatin, mucin, fats etc., from tissues 

 such as "ligamentum nuchae." Some of the more important ways 

 in which it differs from the substances which have been previously 

 described are sufficiently stated by describing the method of its prepa- 

 ration in a pure form 8 . Ligamentum nuchae of an ox is cut into fine 

 slices, treated for three or four days with boiling water, then for some 



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



2 Krukenberg, Zt. f. Biol. Bd. xx. (1884), S. 307. Morner (Swedish). See 

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



3 Petri, Ber. d. deutsch. diem. GeselL Jahrg. xn. (1879), S. 267. 



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



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



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



7 Krukenberg, Morner, loc. cit. 



8 Horbaczewski, Zt. f. phijsiol. Chem. Bd. vi. (1882), S. 330. Chittenden and 

 Hart, Zt. f. Biol. Bd. xxv. (1889), S. 368. 



