Because moisture, which the root absorbs from the earth, is necessary to enable the germ to use the nutrition which the seed itself contains, and out of which the leaf must be eliminated. Moisture forms a kind of gluten, in which the starch of the seed is dissolved, and converted into sugar, the sugar into carbonaceous sap, and the sap into cellular tissue and woody fibre, as the leaves present themselves to the influence of the air and light.

1154. Why does a plant grow?

Because, as soon as membranes and vessels are organised in the young germ, the nutritive fluid, formed by its first organs, begins to move through the fine structures, and from that time the plant commences to incorporate with its own substance the elements with which it is surrounded, that are suitable to its development.

"Can the rush grow up without mire? can the flag grow without water? Whilst it is yet in his greenness, and not cut down, it withereth before any other herb."—Job viii.

CHAPTER LIX.

1155. Why, if we break the stem of a hyacinth, do we see a glutinous fluid exude?