22 PLANT LIFE ON THE FARM. 
CHAPTER IT. 
NUTRITION (Continued)—THE MACHINERY. 
Roots: their nature.—Root-cap.—Root-hairs.—Root action.—Absorp- . 
tion.—Leaves and leaf action.—Chlorophyl].—Absorption of fluid 
and gases.—Leaf work by day and by night.—Oxidation and De-oxi- 
dation.—Carnivorous plants.— Transpiration.—Circumstances pro- 
pitious to it.—The stem and its work.—Its characteristics and vari- 
eties.—Buds.—Branches.—Tubers.—Bulbs.—Uses of the stem.—As- . 
cent of liquids.—Sap currents. 
Roots: Their Nature, Etc.—So far as regards the ab- 
sorption of those food materials derived from the soil by 
the means above-mentioned, the root and its sub-divisions 
are the agents through which the absorption takes place. 
It is not necessary to allude to-the various forms and 
modifications of roots which form the study of the bot- 
anist further than to say that their manifold differences 
of form depend chiefly on the relative proportion that 
the body of the root bears to its branches. If, as ina 
““tap-root,” like a carrot, the body is large, the branches 
are small; if, as in the “fibrous root” of a grass, the 
body is small, the branches are numerous and long. 
In ordinary language a great many things aré called 
roots which are net strictly so. For most people all parts 
of the plant situate below the surface of the ground are 
roots or portions of roots. Botanists, having regard 
alike to the origin, mode of growth, structure, and uses 
of roots, are enabled to define roots partly by positive, 
partly by negative characters. Thus roots originate be- 
neath the surface, that is from within the tissues of the 
plant (endogenous), and force their way out through the 
rind, as contrasted with branches and leaves which orig- 
inate on the surface (exogenous). The extreme tip of 
the root, and of its sub-divisions, is furnished with a mi- 
nute ‘‘root-cap” of dead tissue pushed off from the tip 
