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PHYSIOLOGY: LA NGWORTHY AND HOLMES Proc. N. A. S. 
are of equal interest in the consideration of general problems of nutrition 
and the economic utilization of the food supply under normal conditions. 
The flours studied were prepared from the wheat mixture furnished to 
the flour millers by the U. S. Grain Corporation late in 1917. It consisted 
of the following: 
20% choice hard spring (largely Marquis) 
25% 58 lbs. spring 
15% velvet chaff 
25% slightly smutty spring 
10% durum 
5% Kansas and Oklahoma 
At the request of the Food Administration the wheat was so milled by 
commercial flour mills that a uniform series of extractions was obtained. 
As required by the U.S. Food Administration regulations then in force, 
the amount of wheat used was limited in the proportion of 264 lbs. of 58-lb. 
wheat for 196 lbs. of flour. The milling data follow: 
75% out of 72% extraction yielding 54% of the wheat 
95% out of 74% extraction yielding 70% of the wheat 
100% out of 85% extraction yielding 85% of the wheat 
100% out of 100% extraction yielding 100% of the wheat 
For the sake of convenience the above flours will be referred to accord- 
ing to the percentage of the wheat extracted. Described in ordinary com- 
mercial terms, the 54% flour contained only patent flour. The 70% ex- 
traction, that is 95% of 74% extraction, is what is known commercially 
as a 95% patent, or "standard patent" and contained patent, 1st clear, 
and a small portion of the 2nd clear. The 85% flour corresponds to the 
old-fashioned "whole-wheat" flour, and contained patent, 1st clear, 2nd 
clear, Red Dog, and Shorts. The 100% flour corresponds to that known 
formerly as graham flour and contained the entire wheat kernel. 
These experiments were begun before the Food Administration had 
adopted the milling of what was later known as "war flour." The latter 
was sometimes known as "100% war flour," but this did not mean that 
it contained 100% of the wheat. In milling the "war flour," 100 lbs. 
of cleaned wheat was separated into two products: about 75 lbs. of flour 
(never less than 74.3 lbs.) and about 25 lbs. of feed, giving a flour of about 
75% extraction. The 95% patent or 70% extraction flour used in these 
experiments was similar to the "war flour" save that 5% of low grade and 
2nd clear stock had been removed to improve its bread-making quality. 
Feeding experiments were conducted with healthy young men accord- 
ing to the method commonly used by the Office of Home Economics in 
studies of digestibility. 3 
In order to ascertain whether the subjects acquired during the period 
of the experiments any increased tolerance for the coarser flours the squad 
