. The biology of the amphibia. Amphibians. 136 THE BIOLOGY OF THE AMPHIBIA other less conspicuous forms of the same genus is unknown. Gadow (1901) points out that toads of this genus are used to rub on the growing feathers of parrots to change them from green to yellow. Other Glands.—The mucous glands have apparently given rise to a number of hypertrophied and often tubular glands of special functions. Of these, the best known are the glands on the thumbs or chests of various male Salientia during the breeding season. Their secretion is more granular than that of ordinary mucous glands and hel
. The biology of the amphibia. Amphibians. 136 THE BIOLOGY OF THE AMPHIBIA other less conspicuous forms of the same genus is unknown. Gadow (1901) points out that toads of this genus are used to rub on the growing feathers of parrots to change them from green to yellow. Other Glands.—The mucous glands have apparently given rise to a number of hypertrophied and often tubular glands of special functions. Of these, the best known are the glands on the thumbs or chests of various male Salientia during the breeding season. Their secretion is more granular than that of ordinary mucous glands and helps the male to maintain by adhesion his grip on the female. The toes of tree frogs are equipped with pads which are not suction devices, as frequently stated, but elaborate fric- tion and adhesion mechanisms (Fig. 50). The superficial cells of the epidermis are more or less free one from the other and project as so many short bristles against the substratum. The pad is sup- plied with a complex series of tubular glands which pour their adhesive secretion on the surface of the pad. Mucous glands have apparently given rise during phylogeny to another type of gland of totally different functions. The male Plethodontidae develop glands having a slightly granular secretion which apparently serves to attract the female. A patch of these glands on the chin usually becomes enlarged to form a conspicuous pad (Fig. 51). The Plethodontidae are characterized by a naso-labial groove which serves to free the nostril from water (Wilder, 1906). This groove is flushed by a battery of tubular and frequently branched glands which seem to represent merely a ventral extension of the glandular area surrounding the nostril orifice of the species (Fig. 52). The latter cluster of glands keeps the nostrils of Amphibia free from water and Fig. 51.—The glandular area on the chin, the hyper- trophied naso-labial glands, and the elongated premaxillary teeth are characteristic of the males of seve
Size: 1303px × 1918px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookpublishernewyorkmcgr, booksubjectamphibians
