CLASS-ROOM LESSON
Put two or three earthworms into a jar of rich, damp soil, on top of which there is a layer of sand a quarter of an inch thick. Put bits of cabbage, onion, grass, and other plants on the surface and cover the jar with a glass slip or cardboard.
After a few days, examine the jar, noting the number of burrows, the foods selected, the castings, the food dragged into the burrows. Pour water into the jar and observe the actions of the worms. Can an earthworm live in water?
Place an earthworm on a moist plate or board and direct the pupils to study it, as follows:
Distinguish the head from the rear end, the upper from the lower surface. Observe the means of living. To assist in the latter observation, stroke the worm from rear to head and find the four double rows of bristles. Why is it difficult to pull an earthworm out of its burrow?
Find the mouth. Has the earthworm any eyes, ears, or nose? Place a pin in the path of a moving worm and try to explain why it turns aside before touching the obstacle. Test the sensitiveness to feeling. Why is it cruel to put an earthworm on a fishhook?
From the soil castings found in the jar, infer the value of earthworms for enriching and pulverizing soil. (See "Soil Studies", p. 269.)
REFERENCES
Bailey and Coleman: First Course in Biology. Macmillan Co. $1.25.
Crawford: Guide to Nature Study. The Copp, Clark Co. 90 cents.