All annuals have ?brous roots. Biennials live for two years, and only ?ower in the second; they have ?eshy tap-roots, which are meant to serve as a store of food, for the plant to live upon. Trees and shrubs live for many years, and are called perennials. They have fibrous, woody roots. The leaf consists of a foot- stalk and a blade. Ribs and veins spread through the blade, and its surface is set with breathing-pores. The stem, the foot-stalk, the ribs, and the veins carry up the sap. The breathing- pores suck in carbonic acid gas from the air. The sap takes carbon from this gas to feed the plant.
Lesson 49
The Spider"s Web
"Fred, I noticed that when we looked at the spider, we said nothing about the lower half of his body," said Norah.
"No," said Fred, "I left that for another time. Suppose we talk about it now. This part of the spider"s body is very wonderful. It contains the machinery (if I may call it so) for spinning the web. The material for the thread is a gummy fluid, which is prepared inside the body.
