TUNICIN. CH1TIN. 839 



tunicata, and the widely diffused chitin, found in the cuticle-formation of 

 invertebrates, are of interest. 



Tunicin. Cellulose seems, from the investigations of AMBRONN, to occur 

 rather extensively in the animal kingdom in the arthropoda and the mollusks. 

 It has been known for a long time as the mantle of the tunicata, and this animal 

 cellulose was called tunicin by BERTHELOT. According to the investigations 

 of WINTERSTEIN there does not seem to exist any marked difference between 

 tunicin and ordinary vegetable cellulose. On boiling with dilute acid, tunicin 

 yields glucose, as shown first by FRANCHIMONT and later confirmed by WIN- 

 TERSTEIN. By the action of acetic acid anhydride and sulphuric acid, upon 

 tunicate-cellulose, ABDERHALDEN and ZEMPLEN 1 obtained octoacetyl-cellobiose, 

 which also indicates the relationship with the plant cellulose. 



Chitin is not found in vertebrates. In invertebrates chitin is alleged 

 to occur in several classes of animals; it occurs chiefly in cephalopods 

 (sepia scales) and especially in the arthropods, in which it forms the 

 chief organic constituent of the shells, etc. It has been found in the 

 plant kingdom as in fungi (GILSON, WINTERSTEIN 2 ). The question 

 whether there are two or more chitins or whether there is only one 

 is still disputed (KRAWKOW, ZANDER, WESTER 3 ) . No formula can be 

 given for the same reasons (SUNDWIK, ARAKI, BRACK 4 ). 



Chitin is decomposed on boiling with mineral acids and yields, as 

 shown by LEDDERHOSE, glucosamine and acetic acid. HOPPE-SEYLER 

 and ARAKI found, on heating with alkali and a little water to 180, that 

 chitin was split into a new substance, chitosan, and acetic acid, and that 

 this chitosan contained acetyl groups as well as glucosamine. FRANKEL 

 and KELLY as well as OFFER 5 have obtained acetylglucosamine, 

 (C6Hi2NO 5 )COCH3 and acetyldiglucosamine (C^Ifea^OoJCOCHs as 

 cleavage products of chitin, and they consider chitin as a polymeric 

 monacetyldiglucosamine. 



The chitosan which v. FURTH and Russo 6 have obtained as a crys- 

 talline hydrochloric acid combination and which E. LOEWY has obtained 

 as a crystalline sulphate is, according to the latter, a polymeric monacetyl- 

 diglucosamine with at least two monacetyldiglucosamine groups. Accord- 



1 Ambronn, Maly's Jahresber., 20; Berthelot, Annal. de Chim. et Phys., 56, Compt. 

 Rend., 47; Winterstein, Zeitschr. f. physiol. Chem., 18; Franchimont, Ber. d. deutsch. 

 chem. Gesellsch., 12; Abderhalden and Zemplen, Zeitschr. f. physiol. Chem., 72. 



2 Gilson, Compt. Rend., 120; Winterstein, Ber. d. d. chem. Gesellsch., 27 and 28. 

 3 Krawkow, Zeitschr. f. Biol., 29; Zander, Pfluger's Arch., 66; Wester, Chem. 



Centralbl., 1909, II. 



4 Sundwik, Zeitschr. f. physiol. Chem., 5; Araki, ibid., 20; Brach, Bioch. Zeitschr., 

 38. 



5 Ledderhose, Zeitschr. f. physiol. Chem., 2 and 4; Araki, 1. c., Frankel and Kelly, 

 Monatshefte f. Chem., 23; Offer, Bioch. Zeitschr., 7. 



6 v. Fiirth and Russo, Hofmeister's Beitrage, 8; Loewy, Bioch. Zeitschr., 23; Brach, 

 I.e. 



