“That, like the seeds which we grew in water, bulbs and corms contain a store of food,” said Frank. [Illustration] A. Narcissus Bulb split open. s., stem; b., side buds; s.l., scale-leaves; f.l., leaves. B. Snowdrop Bulb. C. Flower of same Dissected out. “That is correct, Frank. Let us put a corm and a bulb in water. Let us also plant one of each in a pot of soil. We will watch them growing and compare them from week to week. “Now I am going to show you a simple experiment. You know that the food we eat is drawn largely from plants. This food which we take from the plant world is chiefly what the chemist calls _starch_. We have it in bread, potatoes, rice, cornflour, and in nearly all the vegetables we eat. “I have here in this bottle a substance, called _iodine_, dissolved in water. Anything containing _starch_ turns blue when touched with iodine. Now observe what happens here.” Uncle George poured some of the iodine into a saucer. He then dipped into the iodine a piece of crocus corm, a thick scale of the snowdrop bulb, soaked seeds of maize and wheat, a slice of raw potato, and a piece of bread. Each at once turned dark blue on being dipped into the liquid. “Now, boys,” he said, “what do you learn from this?” “The food store in bulbs and corms is the same as that in seeds,” said Tom. “The food supply of the bulb is contained in the thick, fleshy scale-leaves, while in the corm it is in the stem,” said Frank. “Very good,” said Uncle George. “It also shows us, I think, that we ourselves owe a great deal to the plant world.” Exercises on Lesson II. 1. Split an onion (or tulip bulb) down the centre, and compare it with the snowdrop bulb. Draw it, giving special attention to the middle part. 2. Take a potato and a crocus corm. Observe them both carefully, and find out (1) how they resemble each other, and (2) how they differ. 3. Explain how it is that a hyacinth grows so well in water. 4. Take any underground stem (_e.g._, iris or Solomon’s seal) and compare it with a crocus corm. Notice the marks of underground scale-leaves on the former. III.—WHAT GOES ON INSIDE A PLANT. “We have seen how an ordinary twig is built up,” said Uncle George. “Let us now try to find out what goes on inside the twig; and in order to do this we shall have to perform one or two simple experiments.” Uncle George took two wide-mouthed glass jars. They were both perfectly dry, and each could be closed with a large, tight-fitting cork. He placed some fresh green leaves inside one of the jars. The other remained empty. Then both jars were tightly corked up, and both corks covered outside with wax. [Illustration: First Experiment.] “That is experiment number one,” he said, as he placed both jars in the window.