. Animal studies. THE LIFE CYCLE 267 a few easily perceived changes in its post-embryonic devel- opment, of an insect with an "incomplete metamorpho- ; The eggs of grasshoppers are laid in little packets of several score half an inch below the surface of the ground. When the young grasshopper hatches from the egg it is of course very small, but it is plainly recognizable as a grasshopper. But in one important character it dif- fers from the adult, and that is in its lack of wings. The adult grasshopper has two pairs of wings; the just hatched young or larval grasshopper has no wi
. Animal studies. THE LIFE CYCLE 267 a few easily perceived changes in its post-embryonic devel- opment, of an insect with an "incomplete metamorpho- ; The eggs of grasshoppers are laid in little packets of several score half an inch below the surface of the ground. When the young grasshopper hatches from the egg it is of course very small, but it is plainly recognizable as a grasshopper. But in one important character it dif- fers from the adult, and that is in its lack of wings. The adult grasshopper has two pairs of wings; the just hatched young or larval grasshopper has no wings at all. The young grasshopper feeds voraciously and grows Fig. 146.—Post-embryonic development (incomplete metamorphosis) of the Kocky Mountain locust {Melanoplus spretus). a, b, c, d, e, and /, successive develop- mental stages from just hatched to adult individual.—After Emerton. In a few days it molts, or casts its outer skin (not the true skin, but a thin, firm covering or outer body wall com- posed of a substance called chitin, which is secreted by the cells of the true skin). In this second larval stage there can be seen the rudiments of four wings, in the condition of tiny wing pads on the back of the middle part of the body (the thorax). Soon the chitinous body covering is shed again, and after this molt the wing pads are mark- edly larger than before. Still another molt occurs, with another increase in size of the developing wings, and after a fifth and last molt the wings are fully developed, and. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Jordan, David Starr, 1851-1931; Kellogg, Vernon L. [from old catalog].
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Keywords: ., bookauthorjordanda, bookcentury1900, bookdecade1900, bookyear1903
