A Study of Colorado Wheat ‘ 109 
0.41 foot to 3.28 feet, without discovering that the amount of water 
per se, provided that the plant does not actually suffer for the want of 
water, has any influence upon the composition of the wheat, or this 
influence is so small that it is concealed by the influence of the other 
soil factors. Both the amount of water and the manure had an influ¬ 
ence upon the volume of the crop, but no influence upon its composi¬ 
tion. 
Knowing nothing to the contrary, I assume that the weather was 
bright and the plants themselves were uniformly dry exteriorly, and 
grew iirh sunshine and with good ventilation, that is, there was 
no lodging and the air circulated freely between the plants. The 
total rainfall at Boise, Idaho, for May, June, July and August, 1914, 
was 2.39 inches. 
WHY PROTEIN CONTENT IS MOST SIGNIFICANT FACTOR IN THIS 
STUDY 
I have followed others in considering the amount of protein con¬ 
tained in the grain the most significant compound for the purposes I 
^have had in view- This is justified, both by the important part that 
it plays in the use to which the grain is put, principally bread-mak¬ 
ing, and also by the fact that it varies greatly in quantity in proportion 
to the amount present. The starch, which in its total quantity exceeds 
the I'rotein by four or five times, varies less as a rule than it.' The 
method of determining the nitrogen is, probably, the most accurate one 
used in the ordinary analysis of the grain, so that it forms the best 
single analytical criterion for the estimation of the probable quality of 
the wheat. The other compounds are present in relatively small pro¬ 
portions and small percentage variations may really have great sig¬ 
nificance in regard to'the living processes of the plant, but they are 
more difficult both to establish and to interpret. A plant physiologist, 
perhaps, might make out the reasons for, and the significance of the 
fact that the crude fiber in the Marquis wheat may vary 0.70 percent 
when grown in different localities. But, considering the difficulties 
in making this determination a real close one, and the fact that the 
amount of the fiber which is largely contained in the bran varies but 
little from 2.8 percent, it would seem, in the main, unwise to give this 
constituent any prominence. The same may be said of the phosphorus, 
but not with the same justice, for the determination can be made with 
an exceedingly high degree of accuracy and though its quantity is 
small, this quantity can be shown to bear a general relation to the 
amounts of other substances present in the grain and eventually in the 
soil. In Ohio Bulletin 221, p. 22, for instance, the author, J. W. Ames, 
says: ^‘Phosphorus applied to the soil, showing a deficiency of this ele¬ 
ment as measured by crop yields, increases the amount of phosphorus in 
