4 BULLETIN 751, U. S. DEPARTMENT OF AGRICULTURE. 
form experimental conditions were maintained, it is perhaps fair 
to consider all of these digestion experiments as a group. The 
digestibility of white flour obtained by averaging the 31 tests noted 
above is 88:1 per cent for protein and 95.7 per cent for carbohy- 
drate; the digestibility of entire wheat flour obtained by averaging 
the 23 tests is 81.9 per cent for protein and 94 per cent for carbo- 
hydrate; and the digestibility of graham flour obtained by averaging 
the 24 tests noted is 76.9 per cent for protein and 90.6 per cent for 
carbohydrate. 
Considering these tests as a whole, it appears that the protein and 
carbohydrate are more completely assimilated from white flour than 
from entire wheat or graham flours, the last being the least assimi- 
lated; or in other words, the increasing of the amount of bran 
included in a flour is accompanied by a corresponding decrease in 
its digestibility. 
A number of investigations have been conducted in European 
countries to determine the effect on digestibility of including more 
or less bran in the flours prepared from wheat and other cereals. 
Among the earlier studies of the nutritive value of wheat is a 
study by Rubner,' who determined the digestibility of the protein 
present in three flours milled so as to contain 30 per cent, 70 per cent, 
and 100 per cent of the wheat kernel. He found that the protein of 
the 30 per cent flour was 79.3 per cent digested, the protein of the 70 
per cent flour was 75.4 per cent digested, and the protein of the 100 
per cent flour 69.5 per cent digested. Blyth? conducted a series of 
experiments to determine the digestibility of wheat meal (flour pre- 
pared from the entire wheat kernel) when eaten without the addi- 
tion of other food materials. In one experiment of 29 days di- 
vided into three periods, during the first period of 8 days 81 per cent 
of the protein supplied by the 16 ounces of wheat meal eaten daily 
was digested, during the second period of 14 days 82 per cent of the 
protein of 20 ounces of meal was digested, and during the third 
period of 7 days 84 per cent of the protein of 28 ounces of meal was 
digested. In a second experiment of 7 days’ duration in which the 
diet consisted of whole meal and distilled water, the subject digested 
90 per cent of the protein supplied by the meal eaten, which varied 
from 16 to 22 ounces daily. 
Pugliese ® conducted studies to determine the effect of milling on 
the digestibility of wheat flour. He reports that the digestibility of 
the protein of flour containing 85 per cent of the wheat kernel is 
10 per cent less than the digestibility of the protein of flour con- 
- taining 75 per cent of the wheat kernel. 
1 Ztsehr. Biol. 19 (1883), pp. 45-100. 
2 Proc.. Roy. Soc. [London], 45 (1888-89), ‘No. 279, pp. 549-553. 
2 Rev. Gén. Sci., 26 (1915), No. 21, pp. 612-617. 
