If observations on the developments of two forms are carried on at one time, interesting comparisons can be made on such points as, shape and size of the eggs, time required for development, shapes and colours of the tadpoles, activity of the tadpoles, etc. THE EARTHWORM ~Time.~--May or June, in connection with gardening, when the working of the worms in the moist soil of the garden is quite noticeable. Outdoor studies may be assigned, as: Observe the loose soil at the entrance to the burrows. Insert a straw in the burrow and, following it, dig downward with a garden trowel and learn the nature of the earthworm's home. Are earthworms ever found out of their burrows during the day? If so, on what kind of days? Why do earthworms burrow deep in dry weather? Earthworms can breathe only when the surfaces of their bodies are in moist conditions. Go out at night with a lantern to where earthworms are known to have burrows, observe the worms stretched out with the rear ends of their bodies attached to the burrows, and note how quickly they draw back when they are touched. Do they draw back if the ground is jarred near them? Do they draw back when the light falls upon them? State the facts which are taught by the observations which were made on the above topics. 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. Kellogg: _Elementary Zoology._ Holt & Co. $1.35. THE AQUARIUM