a\ 
DIGESTIBILITY OF WHEAT BRAN. 7 
sauce 95 per cent digested. As a rule cellulose of fruits and vege- 
tables seems to interfere with their digestion to a limited extent only. 
In grains, on the other hand, the cellulose forms the hard dry en- 
velope and is much more impervious to the action of the digestive 
juices. With this fact in mind Finkler+ attempted to devise a process 
for milling wheat which would render the bran more digestible and 
which would liberate the protein inclosed within the cellulose walls. 
He recommends the milling of wheat in a solution of sodium chlorid 
or a solution of sodium chlorid containing lime. He states that arti- 
ficial digestion experiments show the protein of the “finalmehl ” ob- 
tained by this process is as completely digested as the protein of white 
flour. 
While a consideration of the results of the numerous digestion ex- 
periments made with different types of wheat flours leads to the con- 
clusion that wheat bran is not as well assimilated as the interior 
portion of the wheat kernel, a review of the literature has failed to 
reveal any data on the digestibility of wheat bran when eaten in a 
diet which did not contain any portion of the remainder of the wheat 
kernel. It would seem that definite data regarding the digestibility 
of wheat bran when eaten in a diet containing no wheat flour are of 
material value in connection with the consideration of the effect of 
different percentages of milling of wheat upon the digestibility of 
the protein and carbohydrate contained in the resulting flours, and it 
was for the purpose of securing such data that the experiments here 
reported were undertaken. 
METHODS OF PROCEDURE. 
The methods employed in this investigation, especially the way the 
bran was prepared for eating, were essentially the same as those fol- 
lowed in experiments to determine the digestibility of nonsaccharine 
grain sorghums and millets. 
In the investigations previously reported in which the digestibility 
of bran has been considered, the bran was referred to as “ fine bran ” 
or “very fine bran,” but in the majority of instances no definite data 
are given regarding the coarseness or fineness of the bran used, and, 
accordingly, it is impossible to make a direct comparison of the 
results of the different studies. 
In the study here reported the size of the bran particles received 
special attention, both fine and coarse bran being included in the 
tests, in order to determine the effect of this factor upon laxative 
properties. An ordinary commercial wheat bran secured in the open 
market was ground until relatively fine in the experimental mills of 
the Bureau of Chemistry. On bolting, all the ground bran passed 
1Jour. Roy. Inst. Pub. Health, 19 (1911), No. 4, pp. 198-199, pls. 2. 
