. Animal life as affected by the natural conditions of existence. Animal ecology. OKIGIN OF LARVA-FORMS. 127 as insects, in the well-known walking-stidr-insects, allies of the grasshoppers (fig. 32), which resemble a more or less dried-up twig or shoot. Many of these species are wingless, so that they bear a wonderful resemblance to the larvse of other, winged forms. If then we assume that the wingless forms are the progenitors of winged forms, the origin of the winged forms may be very well explained by the further assumption that the optimum temperature necessary for maturing the e^s may hav
. Animal life as affected by the natural conditions of existence. Animal ecology. OKIGIN OF LARVA-FORMS. 127 as insects, in the well-known walking-stidr-insects, allies of the grasshoppers (fig. 32), which resemble a more or less dried-up twig or shoot. Many of these species are wingless, so that they bear a wonderful resemblance to the larvse of other, winged forms. If then we assume that the wingless forms are the progenitors of winged forms, the origin of the winged forms may be very well explained by the further assumption that the optimum temperature necessary for maturing the e^s may have been raised so much as to afford more time for assimilar. Fig. 22.—FJtasma sp., a wingless orfhopterous insect. tion and growth, and consequently for more extensive modifica- tions of structure. If, on the other hand, we regard the wing- less species as the later form and derived from the winged species, their origia may be easily explained by assuming that the optimum of temperature for the maturing of the eggs was lowered, while the optimum for growth remained the same. For we know that in many cases, particularly among insects, the life of the individual ends as soon as the eggs are mature and deposited, and that the performance of this function seems. 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 Semper, C. (Carl), 1832-1893. New York, D. Appleton
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