48 MAINE STATE COLLEGE 



materials and the average of all the experiments is but little higher 

 than the corresponding average for the fibre. Indeed from the 

 data at hand it would appear that of all the food constituents 

 capable of individual estimation, these are among the less soluble 

 in the digestive fluids, although commonly included among those 

 substances which are regarded as in a high degree digestible. 



Not only do the pentosans seem to be of low digestibility, but 

 according to Ebstein, the pentoses derived from them by hydroly- 

 sis (arabinose and xylose) are little, if at all assimilated, although 

 readily soluble. He has lately shown that the pentose sugars even 

 in very small quantities are not assimilated by the human organism. 

 Xylose taken in doses of less than one dram by healthy persons, 

 could be recognized in the urine after two or three hours, and 

 hence the use of these sugars even by healthy and much more by 

 diabetic persons could yield no beneficial results. In this connec- 

 tion it is of interest to remember that the pentoses are also non- 

 fermentable. As regards their physiological behavior, they are 

 evidently quite distinct from the hexoses, although otherwise 

 resembling them in chemical characteristics. It is not surprising y 

 therefore, that the less soluble mother substance the pentosans, 

 should also prove less digestible than other carbohydrates. In the 

 light of Ebstein's observations, there is, moreover, good reason for 

 believing that even such portions of the pentosans as are dissolved 

 in the digestive tract are, after all, not assimilated. 



Chemical Laboratory, Purdue University, November, 1892. 



SUMMARY. 



(1) A study of the digestibility of the whole corn plant shows 

 it to have a high percentage digestibility as compared with hays 

 and other coarse fodders, especially when allowed to develop to 

 maturity. Of ten samples of Timothy hay, 57 per cent of the dry 

 matter has proved to be digestible, while of Flint corn fodder 

 (whole plant, mature) 71 per cent was digested. 



(2) The mature Flint corn has proved to be more digestible 

 than the immature Dent corn, the relation for all trials of fodder 

 and silage being as 72 : 65. 



(3) This large difference of digestibility of the two varieties of 

 corn as harvested in Maine is undoubtedly due to the greater pro- 

 portion of fiber in the Dent corn and to the larger relative amount 

 of entirely digestible sugars and starch in mature Flint corn. This 



