1895.] PUBLIC DOCUMENT — No. 33. 175 



2. CONCERNING THE DIGESTIBILITY OF THE 

 PENTOSANS. 



By J. B. LiNDSEY AND E. B. Holland. 



During the past five or six years much attention has been 

 given to the study of the pentosans. Fischer, Tollens, 

 Schulze, Stone and many others have investigated their 

 chemical character, and noted their very general occurrence 

 in our woods and agricultural plants and seeds. 



The pentosans have the composition (G-,Hj.04)n, and by 

 inversion with dilute mineral acids yield, so far as known, 

 two sugars, namely, xylose and arahiiiose, CyHnjO^. The 

 pentosan which yields xylose is more generally found in our 

 agricultural plants. Pentoses* {C.-)l^(f)-^ have been found 

 to exist in the juices of a great variety of growing plants. 

 Whether they are formed by direct assimilation, or from the 

 hexoses, is not yet fully settled- Xylan and araban belong, 

 generall3^ speaking, to the so-called hemicelluloses. E. 

 Schulze f has applied this name to those portions of the cel- 

 lular structure of plants that are not solul)le in water, but 

 in dilute mineral acids. That they cannot always be strictly 

 considered as hemicellulose is made clear from the recogni- 

 tion by Schulze and Winterstein | of a pentosan in amyloid^ 

 a substance extracted with water from the seeds of Tropa?- 

 olum majus. In some cases, also, they approach in char- 

 acter the true cellulose. § Schulze || has also recognized the 

 pentosans in the cotyledons and endosperms of many seeds, 

 and they undoubtedly serve, just as do galactan, starch, etc., 

 as a reserve material, supporting the life of the young plant 



* G. de Chalmot, Am. Chem. Jour., 15, 21. 



t Zeitschr. f. physiol. Chemie, 14. 



X Zeitschr. f. ph.ysiol. Chemie, 13; Berichte der chem. Ges., a4, 2277- 



^ Zeitschr. f . physiol. Chemie, 16 ; also Winterstein loco citato. 



II Loco citato. 



