On the other hand, the ear which is sweet and milky a month before it is ripe, gradually consolidates, the sugar changing into starch, and the milk thickening into the gluten and the albumen[22] of the flour. As soon as this change is nearly completed, or about a fortnight before ripening, the grain contains the largest proportion of starch and gluten; if reaped at this time, the bushel will be heavier, and will yield the largest quantity of fine flour and the least bran.

At this period the grain has a thin skin, and hence the small quantity of bran. But if the crop be still left uncut, the next natural step in the ripening process is, to cover the grain with a better protection, a thicker skin. A portion of the starch of the grain is changed into woody fibre,—precisely as in the ripening of hay, of the soft shoots of the dog-rose, and of the roots of the common radish. By this change, therefore, the quantity of starch is lessened and the weight of husk increased; hence the diminished yield of flour, and the increased produce of bran.

Theory and experience, therefore, indicate about a fortnight before full ripening as the most proper time for cutting corn. The skin is then thinner, the grain fuller, the bushel heavier, the yield of flour greater, the quantity of bran less; while, at the same time, the straw is heavier, and contains more soluble matter than when it is left uncut until it is considered to be fully ripe.[23]

SECTION IV.—ON THE ABSOLUTE QUANTITY OF FOOD
YIELDED BY DIFFERENT CROPS.

The quantity of food capable of yielding nourishment to man, which can be grown from an acre of land of average quality, depends very much upon the kind of crop we raise.

In seeds, when fully ripe, little sugar or gum is generally present, and it is chiefly by the amount of starch and gluten they contain, that their nutritive power is to be estimated. In bulbs, such as the turnip and potato, sugar and gum are almost always present in considerable quantity in the state in which these roots are consumed, and this is especially the case with the turnip. These substances, therefore, must be included among the nutritive ingredients of such kinds of food.

If we suppose an acre of land to yield the following quantities of the usually cultivated crops, namely—

Of wheat, 25 bushels,or  1500lbs.
Of barley,38”or  2000”
Of oats,50”or  2250”
Of peas,15”or  1000”
Of beans,25”or  1600”
Of Indian corn,  60”or  3120”
Of potatoes,10tons,or 22400 ”
Of turnips,25”or 56000”

The weight of dry starch, gluten, sugar, and gum, reaped in each crop, will be represented very nearly by the following numbers:—

Starch. Gluten
and
Albumen. 		Sugar
and
Gum.		 Woody
Fibre.
Wheat,825lbs.315lbs. 60—
Barley,1200”120”160—
Oats,1215”100”250—
Peas,420”260” 20—
Beans,670”370”——
Indian corn,  2100”280” 90—
Potatoes,2688”224”—1253
Turnips,3090”1400”5000—