. A manual of zoology. Zoology. IV. INSECTA: HEX.\PODA 417 From the outer appearance one would conclude that these holometabolous Iarv« not only lacked the wings, but that the appendages of the imago were entirely absent or had an entirely different form; farther, that wings, and frequently antenna;, legs, and mouth parts, come into existence at the moment of pupation, and then in remarkable size and completeness. In fact, the anlagen of all these structures are formed long before pupation, often at the first molt. The wings of a butterfly are present in the caterpillar as small folds or proce
. A manual of zoology. Zoology. IV. INSECTA: HEX.\PODA 417 From the outer appearance one would conclude that these holometabolous Iarv« not only lacked the wings, but that the appendages of the imago were entirely absent or had an entirely different form; farther, that wings, and frequently antenna;, legs, and mouth parts, come into existence at the moment of pupation, and then in remarkable size and completeness. In fact, the anlagen of all these structures are formed long before pupation, often at the first molt. The wings of a butterfly are present in the caterpillar as small folds or processes of the surface which increase in size with each molt. They are not visible because they are pushed into the body and enclosed in sacs opening to the Such anlagen are called imaginal discs (fig. 462); with their recognition the distinctions between complete and incomplete metamorphosis in. Fig. 462.—Diagram of development of wings and legs from the imaginal discs of a fly during metamorphosis (after Lang), /j, larval hypoderinis; j, imagin,al hypoder- mis; /, 'w^ imaginal discs and legs and \nngs formed from them; 5, connection of discs with hypodermis; x, chitinous larval skin. part disappear, since in the first the structures of the imago, even if in a modified shape, are outlined very early. Still there remains much to be remodelled during the pupal rest. The muscles must be adapted to the new locomotor organs, the digestive tract to the altered food, the nervous system re-formed. Since a great part of the larval structures must be broken down to afford material for the reconstruction of the organs, the pulpy nature of the inside of the pupa is easily understood. With a rapid degeneration of the tissues this material is so homogeneous that it was formerly thought that the pupa returned to the indiffer- ent condition of the egg. With the sexual life is connected, in termites and Hymenoptera (bees, wasps, ants), a community formation or social sta
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
