Exercises on Lesson IX. 1. Take in twigs of hawthorn, barberry, holly, bramble, and gooseberry. Examine, and sketch them so as to show their protective parts. 2. Grow a small whin bush in a pot and water it daily. Note that the _new growth_ it makes is tender, and that _no spines_ are produced. 3. Some plants are covered with dense woolly hairs. These are seldom eaten by cattle. Can you explain why? 4. Make a list of all the armed plants you know, and tell how each is protected. X.—THE HORSE POND AGAIN. Frank and Tom returned from the horse pond one day with their jars filled with curious creatures. “We took the water beetle back to the pond, Uncle George,” said Frank, “and I almost felt sorry to let such a cruel and greedy monster loose among the other creatures in the pond.” “You have here creatures even more cruel and greedy than the diving beetle,” said his uncle, looking into the glass jars which the boys had brought. “Here is the larva of the diving beetle, and a fiercer or greedier creature is not to be found in the whole world.” Uncle George refilled the three large tanks. He poured the contents of one of the jars into one of the tanks. It contained, besides the larvæ he spoke of, a number of tadpoles, some small stickle-backs, and a great many water snails or whelks. In addition to these, there were one or two curious insects, with a pair of very long legs. They came to the surface every now and then, and moved their long limbs like oars. Whenever the tank was touched, they would suddenly dive to the bottom. Here they would remain for a short time, then, returning to the surface, would “oar” themselves along as usual. “What are these queer things, Uncle George?” Tom asked. “They look exactly like little boats.” “They are beetles,” Uncle George replied, “and they do resemble little row-boats—so much so that they are called ‘water boatmen.’ This beetle’s body is shaped like a boat, and he lies on his back and moves his very long hind legs exactly like oars. He has a large, sharp beak, which you can see if you look closely.” Just as Uncle George was speaking, a small fly alighted on the surface of the water. It was immediately seized by a water boatman, who dived with it to the bottom of the tank. [Illustration] 1. Water Boatman. 2. Water Whelk. 3. Water Hog Louse. “That is how the creature feeds,” said Uncle George. “When an unlucky fly comes near, he seizes it with his two fore pairs of short legs, drives his cruel beak deep into its body, and dives with it to the bottom of the pool. When he has drowned his victim, he devours it at leisure. “But let us look at the creature I first spoke of—the larva of the diving beetle.”