VARIATION IN COMPOSITION 275 
the proportion or percentage of protein becomes 
smaller as the plant becomes older. The impelling 
purpose of the plant is to produce seed. Whenever 
the water supply begins to give out, or the season 
shortens in any other way, the plant immediately 
begins to ripen. Now, the essential effect of dry- 
farm conditions is to shorten the season; the com- 
paratively young plants, yet rich in protein, begin to 
produce seed; and at harvest, seed, and leaves, and 
stalks are rich in the flesh- and blood-forming element, 
of plants. In more humid countries plants delay 
the time of seed production and thus enable the plants 
to store up more carbon and thus reduce the per cent 
of protein. The short growing season, induced by 
the shortness of water, is undoubtedly the main reason 
for the higher protein content and consequently 
higher nutritive value of all dry-farm crops. 
Nutritive value of dry-farm hay, straw, and flour 
All the parts of dry-farm crops are highly nutri- 
tious. This needs to be more clearly understood by 
the dry-farmers. Dry-farm hay, for instance, be- 
cause of its high protein content, may be fed with 
crops not so rich in this element, thereby making 
a larger profit for the farmer. Dry-farm straw often 
has the feeding value of good hay, as has been dem- 
onstrated by analyses and by feeding tests con- 
ducted in times of hay scarcity. Especially is the 
