APR 29 1924 
On the Carbohydrate Group in Yam Mucin. 
By 
K. Oshima and T. Tadokoro. 
Two kinds of yams, Dioscorea Batatas Dene, and Dioscorea 
j aponica Thunb., are in common use in Japan as an article of food. 
They yield a mucilaginous substance when crushed or grated and extracted 
with water. The chemical nature of this slime was, for the first time, stud- 
ied by J. Ishii 15 . According to him, the slimy matter which is precipi- 
tated from its solution by dilute acetic acid, shows characteristic reactions for 
protein including that of Molisch and yields a reducing substance on boiling 
for some time with 5% sulphuric acid. Basing chiefly upon these reactions 
and its ultimate composition 1 2 3 4 -*, Ishii concluded that the slime belongs to the 
class of mucins. As he, however, made no detailed study 35 concerning the 
presence of a carbohydrate group in his preparation, its relation to the true 
mucins remains yet to be solved 45 . 
1) Bull. Coll. Agric., Imp. Univ. Tokyo, 2, pp. 97 — 100. 
2) Ishii, 1. c. The purified preparation had the following composition: C 52.82, H 7.53, 
N 14.20, O & S 25.05 and ash 0.41. 
3) Too much importance can not be laid upon the Molisch’s reaction, as it is known to 
be too delicate a reaction to be accepted as conclusive evidence of a carbohydrate group in 
the protein molecule. Cf. T. B. Osborne and J. H. hi arris — The carbohydrate group in the 
protein molecule — Jour. Amer. Chem. Soc., 25 (1903), pp. 476—478. That the copper reducing 
property of the hydrolysis product does not give any clue as to the nature of the reducing 
substance needs no comment. 
4) Cf. T. B. Osborne — Die Pflanzen Proteine (Sonderabdruck aus: Asher u. Spiro- 
Ergebnisse der Physiol., 10 (1910), p. 214. 
