LESSON PAGE I. Structure of Stems 7 II. Bulbs and Corms 12 III. What Goes on Inside a Plant 17 IV. Snowdrop, Crocus, and Tulip 23 V. Vegetable Fingers 29 VI. The Great Water Beetle 35 VII. Daisies 40 VIII. Chaffinch and Song-Thrush 46 IX. Plants that Arm Themselves 52 X. The Horse Pond Again 58 XI. Wasps 63 XII. Dandelions 69 XIII. The Life of a Trout 75 XIV. Silkworms 81 Appendix 88 “LOOK ABOUT YOU.” BOOK IV. I.—STRUCTURE OF STEMS. “We are going to have a peep into the inside of these twigs,” said Uncle George, as he laid some willow and horse-chestnut twigs on the table. “First,” he said, “let us examine the outside of them.” He handed a small willow branch to Tom and a horse-chestnut branch to Frank. “Now, Frank, tell me all you see.” “I see the rings of scars which mark each year’s growth,” said Frank. “This year’s growth is at the top, above the first ring of scars. Below this is last year’s growth. Then comes another ring of marks, and below this again is the growth of two years ago.”[1] “That is to say,” said his uncle, “the upper part of your twig is about one year old, the middle part is two years old, and the lower part is three years old. Go on, Frank.” “The upper part is light brown, while the middle and lower parts are dark brown.” “Take your lens, Frank, and look at that brown covering carefully.” “Oh, it is studded all over with little oval marks like pits,” said Frank. “Now, what about the buds?” “The buds,” said Frank, putting down his lens, “are in pairs; and the stem is swollen where each pair of buds comes off.” “Very good,” said Uncle George. “That is exactly what I wanted you to notice. The swollen parts of a stem are called its _nodes_. In every stem, buds and leaves occur at the nodes. Nodes are very well seen in grass and corn stems.” “Then at the top of the twig there is a very large bud and a pair of small buds, one on each side of it,” said Frank. “You have described it very well,” said his uncle. “Now, Tom, what about the willow twig?”