On the Formation of Mannan in Amorpho- 

 phallus Konjak. 



BY 



Michito Tsukamoto, Nogakushi. 

 Professor of Chemistry in Harris' Science School, Doshisha, Kyoto. 



In regard to the formation of carbohydrates, Amorphophallus 

 kovjak is of special chemical interest. The tuber of this araceous 

 plant, from which different articles of food are prepared in Japan, 

 contains, as Tsufi m has shown, no starch, but a very large pro- 

 portion of mannan. Afterwards Kinoshitd® found that the 

 tuber contains two mannans, a slimy soluble one and another 

 insoluble in water. The question suggested itself to my mind : is 

 this mannan produced from glucose by transformation in the 

 tuber, or is the soluble mannan already formed in the leaves from 

 glucose, or finally is mannose a direct product of the assimilation 

 of carbonic acid in the place of glucose in this plant ? Thus far, 

 mannose has never been found in plants except in the form of 

 anhydrides, and it would be no doubt of great physiological in- 

 terest if it could be shown that there exist chlorophyll bodies 

 which produce mannose instead of glucose. 



I examined, therefore, the leaf of this plant and found but 

 very little starch, (3) besides globules not coloured by iodine, and 

 raphides. Further I observed that all portions of the leaf *® 

 contain a very slimy substance which proved to be an anhydride 

 of mannose. The extract prepared with warm water (40°-50° C) 

 was mixed with a large proportion of alcohol and the resulting 

 flocculent precipitate was purified by again dissolving it in water 

 and precipitating once more with alcohol. The aqueous solution 



(1) This Bulletin, vol. II., No. 2. (1894). 



(2) This Bulletin, vol. II., No. 4. (1895). 



(3) I have examined small fragments of the leaf-blade, collected one clear sunny 

 afternoon, with iodine solution under the microscope and found but very few granules 

 were coloured blue. In the ribs there was also only a >-mall amount of starch but 

 relatively more than in the blade-cells. The cellulose walls in the blade gave the 

 ordinary cellulose reaction with sulphuric acid and iodine. 



(4) The leaf stalk and larger portions of the ribs were separated from the leaf blade, 

 including smaller ribs, and both were separately investigated. 



