72 



On the Production of Mannane and the 



Natural Occurrence of Mannose in 



Amorphophallus Konjak. 



By 

 Michito Tsukamoto. 



The Araceous plant Amorphophallus Konjak has a larger tuber from 

 which a peculiar gelatinous food-article called " Konnyaku " is made 

 in Japan. For this purpose, this plant is abundantly cultivated 

 throughout the country. In some analytical report it is stated that 

 the Konnyaku contains starch (6.14 ^) but this is very doubtful, be- 

 cause the Konnyahu does not give the proper starch reaction with 

 iodine solution. Two years ago my friend, C. Tsuji, Nogakushi, in- 

 vestigated the tuber of the plant in the chemical laboratory of the 

 Agricultural College, Imperial University and proved that the tuber 

 contains no starch but is very rich in a different carbohydrate, one of 

 the anhydride of a sugar mannose, to which Schulze gave the name 

 "Mannane." 13 During the next year, it was further 'found by Y. 

 Kinoshita, Nogakushi, in the same laboratory, that the tuber contains 

 not one but two kinds of mannane, one of them, forming the larger 

 portion, being insoluble in water while the other is soluble and forms 

 a slimy solution. 23 



It seems to me to be of very great physiological interest to solve 

 the following questions : whether the mannane is produced in the tuber 

 by transformation from glucose or is the soluble mannane formed in 

 the leaves from glucose and carried down to the tuber ; and lastly in 

 this plant is mannose formed instead of glucose as a direct product of 

 assimilation of carbon dioxide. Thus far, after mannose was first ob- 

 tained by E. Fischer and J. Hirschberger by the oxidation of man- 

 nitol with nitric acid, 35 K. Gans and B. Tollens, 4) Keiss 5) and others 



U The Bulletin of the Agricultural College, Imperial University, Tokyo, Japan; Vol. II, 

 No. 2. (1894) p. 104—105. 



*) The Bulletin: Vol. II, No. 4. (1895) p. 205—206. 



3) Berichted. Dent. Chera. Ges. B.I. 21. (1888) S. 1805. 



4) The Bericlite Bd. 21. (1888) S. 2180. 



C 5 The Bericlite Bd. 22. (1889) S. 609 ; he gave at first the name " Serainose " to his 

 sugar, but afterwards E. Fischer identified that sugar as mannose. 



