=For dissecting=, one needs a lens for the examination of the smaller parts of plants and animals. It is best to have the lens mounted on a frame, so that the pupil has both hands free for pulling the part in pieces. An ordinary pocket lens may be mounted on a wire in a block as in Fig. A. A cork is slipped on the top of the wire to avoid injury to the face. The pupil should be provided with two dissecting needles (Fig. B), made by securing an ordinary needle in a pencil-like stick. Another convenient arrangement is shown in Fig. C. A small tin dish is used for the base. Into this a stiff wire standard is soldered. The dish is filled with solder to make it heavy and firm. Into a cork slipped on the standard, a cross wire is inserted, holding on the end a jeweller’s glass. The lens can be moved up and down and sidewise. This outfit can be made for about seventy-five cents. Fig. D shows a convenient hand-rest or dissecting-stand to be used under this lens. It may be 16 in. long, 4 in. high, and 4 or 5 in. broad. Various kinds of dissecting microscopes are on the market, and these are to be recommended when they can be afforded. [Illustration: _A._—IMPROVISED STAND FOR LENS.] [Illustration: _B._—DISSECTING NEEDLE ½ natural size.] [Illustration: _C._—DISSECTING GLASS.] [Illustration: _D._—DISSECTING STAND.] Instructions for the use of the compound microscope, with which some schools may be equipped, cannot be given in a brief space; the technique requires careful training. Such microscopes are not needed unless the pupil studies cells and tissues. CHAPTER VII THE ROOT—THE FORMS OF ROOTS =The Root System.=—The offices of the root are _to hold the plant in place_, and _to gather food_. Not all the food materials, however, are gathered by the roots. [Illustration: FIG. 32.—TAP-ROOT SYSTEM OF ALFALFA.] [Illustration: FIG. 33.—TAP-ROOT OF THE DANDELION.] The entire mass of roots of any plant is called its =root system=. The root system may be annual, biennial or perennial, herbaceous or woody, deep or shallow, large or small. =Kinds of Roots.=—A strong leading central root, which runs directly downwards, is a =tap-root=. The tap-root forms an axis from which the side roots may branch. The side or spreading roots are usually smaller. Plants that have such a root system are said to be _tap-rooted_. Examples are red clover, alfalfa, beet, turnip, radish, burdock, dandelion, hickory (Figs. 32, 33). A =fibrous root system= is one that is composed of many nearly equal slender branches. The greater number of plants have fibrous roots. Examples are many common grasses, wheat, oats, corn. The buttercup in Fig. 34 has a fibrous root system. Many trees have a strong tap-root when very young, but after a while it ceases to extend strongly and the side roots develop until finally the tap-root character disappears. [Illustration: FIG. 34.—A BUTTERCUP PLANT, with fibrous roots.]