CHAP. VII.] THE CONNECTIVE TISSUES. 271 



According to Fischer and Boedeker, this body is laevo-gyrous and is 

 capable of undergoing the alcoholic fermentation. According to 

 Hoppe-Seyler 1 , the body which reduces cupric salts is a nitrogenous 

 body and is identical with the body obtained by boiling mucin with 

 dilute acids. 



"When chondrin is subjected to prolonged boiling with dilute 

 sulphuric acid, it yields leucine, but no tyrosine or glycocine. 



(Hoppe 1 ). 



When chondrin is heated with barium hydrate, Schiitzenberger and 

 Bourgeois 2 have found that the products of decomposition are some- 

 what different from those yielded by gelatin under the same circum- 

 stances. In both cases carbon dioxide, oxalic and acetic acid, and 

 ammonia are obtained, in addition to a mixture of amido-acids. The 

 quantity of acetic acid yielded by chondrin is, however, three times as 

 great as that yielded by gelatin. In the mixture of amido-acids no 

 glycocine is present. 



Doubts as Amongst the tissues which are supposed to be 



to the exist- composed mainly of chondrigen is the substance of the 

 ence of Chon- cornea. In an investigation on the chemical composition 

 of this structure, Morochowitz 3 has arrived at the 

 conclusion that the primitive fibrillae of the ground substance of 

 the cornea consist of collagen, and that the supposed chondrin is a 

 mixture of gelatin and mucin. After extracting the tissue with lime- 

 or baryta-water or with lOp.c. solution of NaCl, it yields on being 

 treated with boiling water pure gelatin. From the alkaline solutions 

 mucin can be thrown down by the addition of an acid. Morochowitz 

 has further investigated cartilage from various sources, and has found 

 that after treatment with reagents which dissolve mucin, as lime- or 

 baryta- water, 10 p.c. solution of NaCl, or J p.c. solution of caustic 

 soda, whilst mucin is removed, the substance which is left undissolved 

 is on boiling readily converted into perfectly normal gelatin. Accord- 

 ing to this author chondrin is to be looked upon as no pure substance, 

 but as a mixture of gelatin, mucin and salts. 



If these views be, as the Author believes, correct, all the tissues 

 belonging to the connective tissue group, possess common chemical 

 character in that their ground substance is in all cases a body 

 transformed into gelatin by the prolonged action of boiling water; 

 this being mixed in greater or less proportion with mucin which, 

 as we have shewn, undoubtedly plays the part in many forms of 

 connective tissue of a connecting or cementing substance. 



1 Hoppe, "Ueber das Chondrin und einige seiner Zersetzungsproducte." Journ.f. 

 praJct. Chemie, Vol. LVI. (1852), p. 129. 



a Schiitzenberger et Bourgeois, " Eecherches sur la constitution des matieres col- 

 lagenes." Comptes Rendus, LXXXII. 262. 



3 Morochowitz, " Zur Histochemie des Bindegewebes." Verhandl. d. naturhht. 

 med. Vereins zu Heidelberg, Vol. i. part v. 



