Elements of agricultural chemistry and geology / [Jas. F.W. Johnston].

  • James Finlay Weir Johnston
Date:
1844
Catalogue details

Licence: Public Domain Mark

Credit: Elements of agricultural chemistry and geology / [Jas. F.W. Johnston]. Source: Wellcome Collection.

    203/248 (page 187)
    In the blades and stems of the young grasses there is much sugar, which, as they grow up, is gradually changed, first into starch, and then into woody fibre (page 29). The more completely the latter change is effected—that is, the riper the plant becomes—the less sugar and starch, both readily soluble substances, its vaidous parts contain. And though it has been ascertained that woody fibre is not wholly indigestible, but that the cow, for example, can appropriate a portion of it for food as the grass she has eaten passes through her stomach; yet the reader will readily imagine, that those parts of the food which dissolve most easily, are also likely—othei- things being equal—to be most nomdshing to the animal. It is ascertained, also, that the weight of the hay or of the straw we reap, is actually less when they are allowed to become fully ripe; and therefore, by cutting soon after the plant has attained its greatest height, a larger quan- tity, as well as a better quality of hay, will be obtained, while the land also will be less exhausted. The same remarks apply to crops of com,—both to the straw and to the grain they yield. The rawer the crop is cut, the heavier and more nourishing the straw. Within three weeks of being fully ripe, the straw begins to diminish in weight, and the longer it remains uncut after that time, the lighter it becomes and the less nou- rishing. On the other hand, the ear, which is sweet and milkj' a month before it is ripe, gradually consolidates, the su- gar changing into starch, and the milk thickening into the gluten and albumen* of the flour. As soon as this change is nearly completed, or about a foi'tnight before ri])ening, the grain contains the largest proportion of starch and gluten; if reaped at this time, the bushel will * AUmmen is the name given by chemists to tlie luliitc of the c.;/;/ ; a small quantity of this substance is present in every kind of grain. It is closely related to gluten.