. The biology of the amphibia. Amphibians. 400 THE BIOLOGY OF THE AMPHIBIA water temperatures of the region, while others have stressed the importance of a sudden increase of humidity in producing the spring movements (Cummins, 1920; Noble and Noble, 1923). Heavy spring showers usually initiate the migration of salaman- ders of both local and foreign species (Kunitomo, 1910). In the tropics, cooling thunderstorms of the wet season bring forth thousands of loudly calling frogs. Bles (1906) showed the importance of a slight cooling of the water in stimulating the breeding activities of African w
. The biology of the amphibia. Amphibians. 400 THE BIOLOGY OF THE AMPHIBIA water temperatures of the region, while others have stressed the importance of a sudden increase of humidity in producing the spring movements (Cummins, 1920; Noble and Noble, 1923). Heavy spring showers usually initiate the migration of salaman- ders of both local and foreign species (Kunitomo, 1910). In the tropics, cooling thunderstorms of the wet season bring forth thousands of loudly calling frogs. Bles (1906) showed the importance of a slight cooling of the water in stimulating the breeding activities of African water frogs, Xenopus. Frogs are as sensitive to changes of temperature as are human beings (Babak, 1912), and laboratory experiments have shown that salamanders distinguish between regions of different humidities. Fig. 135.—The vocal pouch of Scaphiopus holbrookii. E., Eustachian tube; O., left orifice to pouch. (Shelford, 1914). In addition to temperature and rain, local conditions may affect the migrations of a species. Thus, Piersol (1929) has shown that Ambystoma maculatum of a certain region near Toronto deposited its eggs over an extended season with the maxima about 10 days apart. This was due to the fact that the adults hibernated in two banks which were unequally exposed to the sun. Nevertheless, Amphibia do not always show a close correlation between migration and certain temperature and humidity levels. Storer (1925) found that various western toads and frogs had a protracted breeding season, and other species exhibited a certain correlation between egg laying and times of flood. Migration may in certain cases take place without any external stimulation, for salamanders which are bred in the laboratory frequently retain for a time a periodicity in their egg laying and probably,. 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 perfectl
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Keywords: ., bookcentury1900, bookpublishernewyorkmcgr, booksubjectamphibians
