According to Weismann's theory, which is now well-established, the process of development internally is a much more continuous one than the external changes would indicate. So far as the latter are concerned we simply say that a caterpillar changes to a chrysalis and a chrysalis to a butterfly, the transition in each case requiring but a very short time. Internally, however, it has been going on almost continuously from the early life of the caterpillar. The various organs of the butterfly arise from certain germinal disks or "imaginal" buds, the word "imaginal" in this case being an adjective form of imago, so that the imaginal buds are really simply buds for the starting of growth of the various organs of the imago or adult. As the caterpillars approach the chrysalis period these imaginal buds rapidly develop into the various organs of the butterfly. This process is helped along by the breaking down of many of the tissues of the larva, this broken-down tissue being then utilized for the production of the new organs. About the time the chrysalis is formed this breaking-down process becomes very general, so that the newly formed chrysalis seems largely a mass of creamy material which is soon used to build up the various parts of the butterfly through the growth of the imaginal buds. _The Change to the Butterfly_ (_See plate, pages 32-33._) There is probably no phenomenon in the world of living creatures which has attracted more attention than the change of the chrysalis into the butterfly. It is not strange that this is so. We see upon a tree or shrub or wall an inert, apparently lifeless object, having no definite form with which we can compare it with other things, having neither eyes nor ears nor wings nor legs--an object apparently of as little interest as a lifeless piece of rock. A few minutes later we behold it again and note with astonishment that this apparently inanimate being has been suddenly transformed into the most ethereal of the creatures of earth, with an exquisite beauty that cannot fail to attract admiration, with wings of most delicate structure for flying through the air, with eyes of a thousand facets, with organs of smell that baffle the ingenuity of man to explain, with vibrant antennae, and a slender tongue adapted to feeding upon the nectar of flowers--the most ambrosial of natural food. So it is not strange that this emergence of a butterfly has long been the theme both of poets and theologians and that it attracts the admiring attention of childhood, youth, and age. Fortunately, this change from chrysalis to butterfly may readily be observed by any one who will take a little trouble to rear the caterpillars or to watch chrysalids found outdoors. The precise method of eclosion, as we call this new kind of "hatching," varies somewhat with different species but in general the process is similar in all.