Suddenly, as if it were annoyed at being touched by the pencil, the lower half of the object moved from side to side with rapid jerks. “Why, it is alive,” said Tom. “Yes, of course it is,” said his uncle. “This is another lucky find.” “What are they?” Frank asked. “Can’t you guess, Frank? Don’t you remember my telling you that all the insects were asleep in their cases during winter. “Each of these darker coloured cases contains a white butterfly. They have been here all winter, and they are just about to hatch out.” “How do you know that, Uncle George?” “I know it because the empty cases tell me that some of the butterflies have just hatched out. This is what your cabbage caterpillar becomes after he is tired of feeding. “You have now seen three different stages of the life of this insect. First, the curious eggs laid on the under side of the cabbage leaf; next the greedy caterpillar; and now, the chrysalis or _pupa_ stage. “The caterpillar goes to sleep in autumn as a hard-cased chrysalis, and wakes up in spring a beautiful butterfly.” “How strange,” said Frank. “And will our caterpillars remain caterpillars until autumn, and then tuck themselves up like this and go to sleep for the winter.” “No, Frank! our caterpillars will go into the chrysalis state in a week or so, and hatch out as butterflies in August. These August butterflies will lay eggs. The caterpillars from these eggs will turn into _pupæ_ in September. “These September pupæ will supply the white butterflies of next spring and summer. Put some of these into your box. Watch then carefully, and you may be lucky enough to see the white butterfly coming out of his winter case.” “I cannot understand,” said Tom, “how a big white butterfly can be inside so small a case. It must be very tightly wrapped up.” “So it is, as you will see,” said Uncle George. “Good-bye, boys! and mind, when I come back, I shall expect to see notes and sketches of all that has taken place in the larva cage during my absence.” * * * * * * * * “Won’t you let your uncle take his dinner first,” said Frank’s mother, as she hung Uncle George’s overcoat up in the hall. “No, mother! he must come at once,” said the excited Frank. “There’s a butterfly just coming out.” “Oh, I must come and see that,” said Uncle George; and he allowed his eager nephews to drag him towards the larva cage. By the time they got to the cage the butterfly had hatched, but they were in time to see it unfurl its wings. The wings were crumpled and twisted, but the creature slowly straightened them out to dry in the sun. “We saw it burst its case,” said Tom. “First a small slit appeared at the head end. This slit grew larger. Then the butterfly’s head and feet appeared. It squeezed its way and was just half way out, with its wings crumpled round it, when you arrived.” “I arrived just a minute too late, then,” said his uncle. [Illustration: White or Cabbage Butterfly and Pupa.]