flowers have been made larger, and more beautiful, and of unusual colors; cereals and other grasses have been made more useful and hardy; new foods have been produced for our use. This work of improving our plants is very interesting, and is a field which can never be exhausted. Read something of what Burbank has done.

335. Exercises.

1. Why do lumbermen prefer to get logs out of a northern swamp in winter rather than in summer? When would the wood be more dry?

2. What must be true of the pores of wood, if the wood takes up stains readily?

3. Why should we leave as much soil as possible upon the roots of a tree when transplanting it?

4. What is soap bark? Peruvian bark? For what is each used? For what did the American Indian use birch bark?

5. Put a piece of knotty yellow pine or hemlock in the hot rays of the sun, or near a hot radiator or stove. What happens to the knots? What causes the odor? What material is in the knots?

6. What are the advantages of a wooden house over a brick house? What are the disadvantages?

7. Why does the ink "run" when we try to write upon blotting paper? What phenomenon is this? See § 125.

8. Name some plants that scratch you when you touch them. Some that poison you. Some that have a disagreeable odor.

9. How can a tree be protected from caterpillars that crawl up its trunk?

10. Find out the meaning of chrysanthemum. How has the flower been developed to so great a size?

Summary. Trees are our friends because of their beauty, their shade, and the fruit, nuts, wood, and other material they give us. The shape of each kind of tree depends on the way in which its branches are arranged.

The trunks of our common trees have pith at the center, then heartwood, sapwood, the green layer, or cortex, and the epidermis.

Trees with only one cotyledon in the seed have the wood bundles scattered through the pith.

The bark is the old epidermis still adhering to the tree.

Knots are the remains of old branches.

Wood is so useful because it can be fitted together, is light, and

can easily be decorated.

Most of our hardwood comes from deciduous trees, and most softwood from evergreens.

Most of our paper is made from wood pulp.

Arbor Day is set apart for the planting and preserving of trees. A weed is a plant out of place.

Beauty in a lawn or garden depends upon the choice and arrangement of plants.

Man has developed plants by "selection" and by "crossbreeding."

CHAPTER XXXIV

ANIMALS OF IMPORTANCE TO MAN

336. How Many Animals are There? - We have learned something of the wonderful world of plants and how they grow, also how man makes use of such as he wishes, and seeks to destroy those that injure him or his cattle or his cultivated plants. The world of animals is just as wonderful as that of plants; perhaps even more So. Think of the number of forms nature has produced, from the tiniest insects to great animals like the whale and the elephant. The microscope shows us forms much smaller than the smallest insects, until, as in the case of plants, we get down to animals having only a single cell. Yet even these tiniest creatures are able to do the things needed to support their life and to produce new beings like themselves (see § 297). Of insects alone men know perhaps more than 200,000 different kinds, or species (spē'shēz); of birds perhaps 10,000; of fishes about 12,000. You will see from these figures that it is hardly possible for one person to know all the animals there are. Besides the animals now living, there are thousands of forms which lived in the past, and which we can know only through their fossils (see § 147). Have you seen some of these animal fossils in museums?

Zoology (zō-Ŏl'ō-jí) is the science of animals; the name comes from the word " zō'on," meaning an animal. What is a "Zoo"? What is its full name?

337. Have Animals Helped, or Hindered, Man's Progress? - When we think of the number of people killed by wild animals, such as tigers, lions, wolves, and snakes, even in recent years, after men had invented powerful weapons

of protection, we may imagine that early man, with his poor weapons, or none at all, had a hard time of it. See Fig. 252. Some animals he killed for food; many others were his enemies, and

FIG. 252.

A drawing of a mammoth, made by early man upon an ivory tusk. After Lartet, but hunted him. But greatly simplified. the story is differ

ent when man had learned to tame animals, and to use them in his work. These animals then became his helpers in his march to civilization. Would it not be interesting if we could have the true story of the way in which man first caught dogs, horses, cows, sheep, goats, and chickens, and made them feel at home with him? To understand man's early history correctly, we must know something of these first pets of his, and how he made them his companions and helpers by domesticating them. What does

domesticate mean? It comes from the Latin word domus, a house, and means that man made these animals a part of his household.

Have you ever thought that while man domesticated certain wild animals, and made a home for them, they, in their turn, helped to keep him at home and to make that home in some one place? For

a long while after man had domesticated animals, he wandered about with his flocks and herds, in search of food and pasture, just as certain nomadic (nō-măd'ik) tribes of Asia and northern Africa do today. Gradually, however, man learned to domesticate, not only animals, but plants also, and to feed the plants, or their seed or fruit, to his animals, and to eat the food himself. Instead of remaining a nomad, he became a farmer, and began to build up communities and nations.

Has man altogether lost his love of hunting wild animals? Think how we still love to hunt and to fish, partly, of course, because of the