The insect's skeleton is on the outside of its body instead of a skin, and the flesh and muscles are supported by it on the inside instead of on the outside like our own. As this skeleton is hard it cannot stretch; as the insect grows and gets too large the shell bursts open and the insect walks out of it. Now underneath this old hard skeleton a new one is formed, which is soft and flexible at first, and so stretches to accommodate the growing insect. After a little time this new skeleton also hardens and has to be shed when it is too small to suit its owner. Notes should be made by the pupil upon the change of color and markings after the different molts, and the process of molting should be described. LESSON IV. THE PUPA. FIG. 149, _d_. In ordinary seasons, about the middle of May, the caterpillars get their growth. If those in the breeding cage have died or have not thrived, bring in a few full-grown caterpillars from the orchard and put them on some branches in the breeding cage. Give them fresh food each day as long as they will eat; also place some sticks and chips on the bottom of the breeding cage for the worms to "spin up" on. Then have the children observe the following things: How do the caterpillars begin their cocoons? Where are the cocoons made? How are they made? Draw a picture of a cocoon. About a week after a cocoon is made, open it carefully with a pair of scissors so as not to hurt the inmate, and let the pupil see the change that has come over the caterpillar. Have the pupils describe the pupa. Let the pupils make drawings of the pupa. The moths will hardly emerge from the cocoons until after the close of the school term. The children should be encouraged to gather the cocoons from the fences around the orchards and from the sticks and the branches on the ground and to carry them home. The cocoons may be placed in pasteboard boxes and kept until the moths emerge, about the middle of July. LESSON V. DESTROYING THE CATERPILLARS. After the caterpillars are fully grown and all the processes of growth have been observed by the pupils, the teacher should give a lesson upon the injury which they do to trees and the necessity of keeping the orchards free from these pests. This lesson should be given guardedly so as not to encourage the children to cruelty in killing insects. The teacher should always try to inculcate in the child reverence for life, that wonderful force, which we can so easily take from a creature but which we can never give back. It is better to appeal to the child's sense of justice in giving this lesson. The teacher may vary it to suit her own ideas, but in substance it might be given somewhat as follows: