“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.