Various kinds of dissecting microscopes are on the market, and these are to be recommended when they can be afforded.
| B.—Dissecting Needle ½ natural size. | C.—Dissecting Glass. | D.—Dissecting Stand. |
| A.—Improvised Stand for Lens. |
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.
| Fig. 32.—Tap-root System of Alfalfa. | 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]).