or other seeds in the tester, and keep record of the number that sprout. The result will give a percentage measure of the ability of the seeds to grow. Note whether all the seeds sprout with equal vigor and rapidity. Most seeds will sprout in a week or less. Usually such a tester must have fresh sand and paper after every test, for mold fungi are likely to breed in it. If canton flannel is used, it may be boiled. If possible, the seeds should not touch each other. [Illustration: FIG. 31.--A HOME-MADE SEED-TESTER.] NOTE TO TEACHER.--With the study of germination, the pupil will need to begin dissecting. =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 jeweler’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 ¹⁄₂ 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.