Uncle Robert's Geography (Uncle Robert's Visit, V.3 - Tapa blanda

Excerpt: ... said Donald. "But the leaves turn yellow in the fall," said Frank, "and the trees do not die." "The leaves of my spruce don't turn yellow in the fall," said Donald. "They stay green all winter." "What makes the leaves green?" asked Uncle Robert. No one answered. "What is the color of the potato sprouts in the cellar?" "Yellow," said Susie. "When you take up a board that has lain on the grass, what is the color of the grass?" "Yellow," said Donald. "Why?" asked Uncle Robert. "Because they don't get any light," said Frank. "You know why we put our plants in the south window in winter?" said Mrs. Leonard. "Oh, yes," said Susie, "because the sun shines in at that window." "Warmth and water and air help trees and plants to grow," said Uncle Robert, "but without sunlight their leaves would be yellow and their stems and branches weak. The greatest forests on earth are where it is very hot and moist. The sun is a wonderful artist, and every leaf it paints makes the tree stronger." "But what makes the leaves turn yellow and red just before they fall off?" asked Frank. "Does the sun paint them then?" "That is a question that no one has been able to answer," replied his uncle. "But how can the sap flow up the tree?" said Donald. "I should think it would run down." "It would unless there was something to draw it up," said Uncle Robert. "I suppose the sun does that, too," said Frank. "Where does it go after it reaches the leaves?" asked Uncle Robert. "Why, back again," said Susie. "No, it doesn't go back-not a drop," laughed Uncle Robert. "Does it dry up?" asked Donald. "What do you mean by drying up?" "It evap-o-rates," said Donald, who liked to use large words. "Does it all go into the air?" asked Frank. "I want you to answer these questions yourselves, children. What do you see on the corn leaves in the early morning?" "Drops of water; but that is dew, isn't it?" asked Frank. Uncle Robert had a way of stopping or changing the subject when he had asked...