MANNANE AS AN ARTICLE OF HUMAN FOOD. 105 



ing at 205°C. The characteristic mannose-oxime was also ob- 

 tained by slow evaporation of a portion of the syrup with a mix- 

 ture of hydrochlorate of hydroxylamine with sodium carbonate 

 and purified by recrystallization from absolute alcohol. A por- 

 tion of the sugar-syrup was also repeatedly oxidized with nitric 

 acid to see whether mucic acid could be obtained, but none was 

 found ; therefore no galactan was present in the konniaku root- 

 stock. Also, as no pentose reaction with hydrochloric acid 

 and phloroglucin could be observed, there could not be present 

 in the konniaku-root xylan or araban to any considerable extent. 



If all the sugar obtained was mannose, as is very probable, 

 then the konniaku powder mentioned yielded 55.86% of mannose. 



This konniaku root is evidently very well suited for the 

 preparation of the polyanhydride of mannose called mannane 

 in a pure state. As this mannane is used as food, it must 

 evidently be digested by the enzymes in the intestines and 

 transformed into mannose or a dimannose corresponding to 

 the maltose made from starch, but my attempts to convert the 

 mannane of konniaku by diastase made from malt into a sugar, 

 were not successful. The more interesting then is it that the 

 human intestines can digest mannane. 



