DISTRIBUTION OF PENTOSANS IN THE CORN PLANT 
AT VARIOUS STAGES OF GROWTH 1 
By J. H. VER HulsT, Assistant , W. H. PETERSON, Associate Professor , Department 
of Agricultural Chemistry , and E. B. Fred, Professor , Department of Agricultural 
Bacteriology , Agricultural Experiment Station 
INTRODUCTORY DISCUSSION 
Pentosans are known to be present in the cell walls of all green plants, 
in the bark and woody fiber of trees, in spices, fungi, mosses, various 
straws, tree and vegetable gums, fruits, and seeds. The wide occurrence 
of the pentosans in nature and the large percentage of furfural-yielding 
constituents in the cellular and skeletal structures of various plants has 
led many investigators to make a thorough study of these plant sub¬ 
stances in the hope that some exact knowledge might be obtained con¬ 
cerning their origin and physiological function. 
A study of the pentosan content of plants at various stages in their 
development discloses some significant facts. In most seeds the pento¬ 
sans increase during the process of germination. This increase continues 
throughout the growth of the plant and is particularly marked in the 
fibrous portions such as the straw, the stem, or the leaf. The new tissue 
contains a smaller quantity of pentosans than the old; a young leaf may 
have only about two-thirds as large a quantity of pentosans as a dead 
and withered leaf. The formation of pentosans appears to parallel that 
of the cellulose and to be more particularly concerned with the structural 
requirements of the plant. 
It is generally agreed that pentosans are not directly formed by 
assimilation of carbon dioxid. The increase in the actual quantity of 
pentosans in the germination stage indicates a conversion of hexose 
material into pentosans. This direct evidence for the conversion of 
hexosans into pentosans finds additional support in the discovery that 
xylans are in almost every instance found with glucosans, while arabans 
are most often found together with galactans. (18,14 , 16, 6,) ? In many 
of the straws the xylose molecules are linked with the cellulose molecules 
in such a firm complex that they can only be separated by a strong acid 
hydrolysis. 
Arabinose-galactose complexes (galacto-arabans) have been found in 
legumes, in arabinic acid, in cherry and peach gums, in gum tragacanth, 
and in coffee beans. De Chalmot (2) has pointed out the striking 
similarity between the stereoisomeric formulae of d-glucose and 1-xylose, 
and between d-galactose and 1-arabinose, and in view of this fact has 
proposed a theory to explain the conversion of hex6sans into pentosans 
by the plant. According to this theory the pentoses are formed from 
the corresponding hexoses as a result of oxidation and decarboxylation 
of the terminal alcohol group. The proof for this theory has not been 
established, however, by experimental evidence. 
1 Accepted for publication Sept. 13, 1922. This work was supported in part by a grant from the special 
research fund of the University of Wisconsin. Published with the approval of the Director of the Wisconsin 
Agricultural Experiment Station. 
* Reference is made by number (italic) to “ Literature cited," p. 662-663. 
( 6 S 5 ) 
Vol. XXIII, No. 8 
Feb. 24, 1923 
Key No. Wis.-i9 
Journal of Agricultural Research, 
Washington, D. C. 
acg 
