VARIATIONS IN COMPOSITION 267 
sons. This may be due to the nature of the soil, or 
to the fertilizer applied, though variations in plant 
composition resulting from soil conditions are com- 
paratively small. The greater variations are almost 
wholly the result of varying climate and water supply. 
As far as it is now known the strongest single factor 
in changing the composition of plants is the amount 
of water available to the growing plant. 
Variations due to varying water supply 
The Utah station has conducted numerous ex- 
periments upon the effect of water upon plant com- 
position. The method in every case has been to 
apply different amounts of water throughout the 
growing season on contiguous plats of uniform land. 
Some of the early results are shown by the following 
table : — 
Tue Errect oF WATER ON THE PERCENTAGE COMPOSITION 
oF Puant Parts 
of A PROTEI F FIBER a 
AT 
ec co oe Extract 
Corn Kernels 
7.5 1.62 15.08 6.02 1.89 75.39 
15.0 1.65 13.48 6.16 1.91 76.86 
37.3 1.62 12.52 6.26 1.89 77.72 
