"You shall not make that sacrifice, darling," said Mrs. Merivale; "we will put that all right, and I will go and see Mrs. Brett in the morning." And so the matter was finally arranged, and that the boys might become well acquainted with each other, Dick Carleton was invited to stay at Mr. Merivale's. But before he comes we will just go back a few hours and follow merry Mary Merivale, as her brother called her, and her younger sister Florrie, on their search for pupæ. CHAPTER IV. Digging for Pupæ.--Dick Carleton.--Metamorphoses of Butterfly. About two miles further inland from Mr. Merivale's and in the midst of a fine and well-wooded country, was Sir Richard Carleton's house. Around it was a park with larger timber trees than were to be found in the rest of the countryside. Mary and Florence Merivale had fixed on this spot as the scene of their labours in the cause of science, as represented by the collections of their brother and Jimmy Brett. Leaving the path, they trespassed boldly in search of suitable trees for their purpose. Frank had told them that the vicinity of houses was the best, because moths, in all probability attracted by the lights, laid their eggs on trees and shrubs near houses. So the two girls went up as near the large house as they thought they might venture without being seen, and commenced their search. A tall youth strolling languidly down a path through the woods saw two kneeling figures in red cloaks at the foot of a large willow-tree, and their movements aroused his curiosity, and while he stands looking at them let us say what manner of boy Dick Carleton is. He is very tall and thin, but he has a figure that only wants filling out to be handsome. He has a very beautiful face and head, and curly brown hair. His large dark eyes and pale complexion make him look more delicate than he really is, but he is afflicted with a listless melancholy that shows itself in every movement. It was this melancholy which had aroused his father's fears, and it was plain that if it were not checked in time grave results might follow. He stood for some time looking at the two girls, wishing to ask what they were doing, but too shy to do so. At last Mary caught sight of him, and rising, she said-- "I hope we are not trespassing?" "You are trespassing, but it does not matter," replied Dick, taking off his hat. "But may I ask what you are doing?" "We are digging for pupæ," answered Mary. "And what are pupæ?" "Don't you know?" asked Mary in surprise. "No." "Why they come into moths. The moth lays its egg, the eggs turn into caterpillars, which feed on leaves and trees, and then turn into these things," and she then showed him five or six large red cylindrical objects which she had in her basket. "When the spring comes these will turn into moths." "How wonderful," said Dick. "I did not know that before; but if the caterpillars feed on leaves, how is it that you dig those from the ground?"