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Even the most casual observer has noticed that the various species of amphibians do not frequent the same type of surrouindings. A student of ecology finds that practically every species of amphibian has a distinctive habitat, and that the habitats range from strictly aquatic to almost totally terrestrial. In the transition from the aquatic to the terrestrial mode of life among amphibians, the problem of the conservation of body moisture presents itself. To an aquatic species which is constantly bathed in water, this offers no difficulty. But a terrestrial species is obviously exposed to the effects of evaporation for long periods of time, and therefore must replace the surface moisture lost through evaporation from its reserve within the body. In order to endure a comparatively dry habitat and to cope with the inevitable loss of body water, a terrestrial amphibian evidently must possess some adaptation not present in an aquatic form, or present in a smaller degree. To explore this problem, a series of experiments were performed, in which, under controlled conditions, specimens of several species of amphibians were artificially subjected to drying conditions experienced in milder form in nature. This paper presents (1) data based upon the careful measurement of the water lost through evaporation, (2) a comparison of the limits beyond which individuals of the species studied could not survive exsiccation, (3) a correlation |
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