8 BULLETIN 751, U. S. DEPARTMENT OF AGRICULTURE. 
through the 20-mesh sieve, 68 per cent remained on the 40-mesh sieve, 
20 per cent remained on the TO-mesh sieve, 4 per cent remained on the 
90-mesh sieve, 2 per cent remained on the 109-mesh sieve, and the 
remainder, 6 per cent, passed through the 109-mesh sieve. Two series 
of experiments were conducted, one with the ground bran described 
above and referred to in this paper as " fine wheat bran " and one 
series with unground bran in the form of "flakes" which were a 
part of the lot from which the fine wheat bran was prepared. The 
test periods were of 3-clays' or 9-meals' duration. The urine was 
not collected and no attempt was made to maintain a nitrogen equilib- 
rium, or uniform body weights. The feces were separated in the 
usual way by means of pulverized charcoal taken in gelatin capsules 
with the first meal of the test period and the first meal following the 
period. The foods and feces were analyzed by the usual chemical 
methods. 
SUBJECTS. 
Five different subjects assisted in this investigation and with the 
exception of one subject (P. K.) all took part in the two series of 
tests which were made. These subjects, students in medical or dental 
schools whose ages varies from about 20 to over 40 years, were so 
chosen as to be fairly typical of the average person of this period 
of life. While all were young men of normal appetites and to all ap- 
pearances of good health, they were of quite different temperaments. 
Subject A. J. H., a strong, vigorous young man who had served one 
or two enlistments in the U. ,S. Army and who had seen service in 
the Philippines, possessed a particularly hearty appetite. Subject 
P. K., on the other hand, a man of over 40 years of age, took little 
more than necessary exercise, was studiously inclined, had a tendency 
toward constipation, and would be very properly classed as of 
sedentary habits. The other three subjects, while not representing 
such direct contrasts, were, nevertheless, not in the least alike as 
regards food habits, and kinds and amounts of exercise taken, al- 
though they were of about the same size and age. 
All the subjects were instructed to submit a report of their physi- 
cal condition during the test periods. They were also instructed to 
observe special care in reserving any uneaten portion of the diet 
and in the separation and collection of the feces resulting from the 
experimental diet. 
EXPERIMENTAL DIET. 
Since information regarding the digestibility of the protein sup- 
plied by wheat bran was especially desired, the diet was so chosen 
that the accessory foods should contain a minimum of protein and at 
the same time should not be totally different from an ordinary sim- 
ple mixed diet possessing some variety. The experimental diet con- 
