=Beauty of grain and polish= gives wood value for furniture, pianos, and the like. _Mahogany_ and _white oak_ are most beautiful, although red oak is also used. Oak logs which are first quartered and then sawn radially expose the beautiful silver grain (medullary rays). Fig. 86 shows one _mode of quartering_. The log is quartered on the lines _a_, _a_, _b_, _b_; then succeeding boards are cut from each quarter at 1, 2, 3, etc. The nearer the heart the better the “grain”: why? Ordinary boards are sawn tangentially, as _c_, _c_. _Curly pine_, _curly walnut_, and _bird’s-eye maple_ are woods that owe their beauty of grain to wavy lines or buried knots. A mere stump of curly walnut is worth several hundred dollars. Such wood is sliced very thin for veneering and glued over other woods in making pianos and furniture. If the cause of wavy grain could be found out and such wood grown at will, the discovery would be very useful. _Maple_ is much used for furniture. _Birch_ may be coloured so as very closely to represent mahogany, and it is useful for desks. =Special Products of Trees.=—Cork from the bark of the cork oak in Spain, latex from the rubber, and sap from the sugar-maple trees, turpentine from pine, tannin from oak bark, Peruvian bark from cinchona, are all useful products. SUGGESTIONS.—_Parts of a root and stem through which liquids rise._ =49.= Pull up a small plant with abundant leaves, cut off the root so as to leave two inches or more on the plant (or cut a leafy shoot of squash or other strong-growing coarse plant), and stand it in a bottle with a little water at the bottom which has been coloured with red ink (eosine). After three hours examine the root; make cross sections at several places. Has the water coloured the axis cylinder? The cortex? What is your conclusion? Stand some cut flowers or a leafy plant with cut stem in the same solution and examine as before: conclusion? =50.= Girdle a twig of a rapidly growing bush (as willow) in early spring when growth begins (_a_) by very carefully removing only the bark, and (_b_) by cutting away also the sapwood. Under which condition do the leaves wilt? Why? =51.= Stand twigs of willow in water; after roots have formed under the water, girdle the twig (in the two ways) above the roots. What happens to the roots, and why? =52.= Observe the swellings on trees that have been girdled or very badly injured by wires or otherwise: where are these swellings, and why? =53.= _Kinds of wood._ Let each pupil determine the kind of wood in the desk, the floor, the door and window casings, the doors themselves, the sash, the shingles, the fence, and in the small implements and furniture in the room; also what is the cheapest and the most expensive lumber in the community. =54.= How many kinds of wood does the pupil know, and what are their chief uses?