The development of the eggs of the frog or newt may be studied from preparations made in precisely the same way as those for the study of the development of the toad.
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.