294 Mary Davies Swartz, 



From these experiments, mannan would seem to be well utilized by 

 herbivora. The only experimental data regarding the nutritive value 

 of mannans to man, are cited by Oshima (15) from work by Kano and 

 lishima (255), who found the coefficient of digestibility of konjaku 82 

 per cent (prepared from Conophallus konjaku) . Further investigations 

 seem highly desirable, in view of the fact that in certain regions food 

 stuffs like salep and konjaku, consisting of almost pure mannan, are 

 among the chief articles of the poor man's diet. It is also a question 

 whether the nutritive value of bark, especially of coniferous trees, is 

 due to mannan present. According to Dillingham (239) the quantity 

 of mannan present does not justify such an assumption, aside from 

 the question of its digestibility. 



We have finally to inquire whether ' mannan can be hydrolyzed 

 within the organism, and if so, whether the mannose produced can be 

 retained and form glycogen. From the literature on the subject, it 

 appears that mannose is well utilized by rabbits, dogs and men. Ac- 

 cording to Neuberg and Mayer (260), the d-iorm is better utilized 

 than the /- or i-form. Mannose is readily converted to dextrose in 

 the organism; thus Neuberg and Mayer found that a rabbit, receiv- 

 ing 10 grams of /-mannose per os, excreted 1 gram /-mannose and 4-5 

 grams /-glucose; 10 grams of (/-mannose given rabbits per os, or sub- 

 cutaneously, were almost completely oxidized. Rabbits fed 30 grams 

 (/-mannose by Cremer (238) excreted 3-4 grams in the urine, and dogs 

 given 20 grams by Rosenfeld (265), excreted over 4 grams. This is 

 somewhat more than would be excreted on giving equally large quan- 

 tities of dextrose or levulose. Cremer (238) found no sugar in the 

 urine of a man after feeding 3-12 grams of mannose. 



That mannose can act as a glycogen former in rabbits, has been 

 demonstrated by Cremer (238) and also by Rosenfeld (265). Neu- 

 berg and Mayer (260) found only a small amount of glycogen in the 

 livers of starving rabbits after feeding /-mannose, but even this form 

 is utilized to some extent. There is good reason for assuming, there- 

 fore, that if mannans can be converted into mannose in the process 

 of digestion, they may be considered as true nutrients for the organ- 

 ism, the mannose being to a high degree capable of absorption and con- 

 version into glycogen. 



