Vascularization of Respiratory Surfaces in Some Caudata

Abstract

The investigations concerned the vascularization of respiratory surfaces of eight species of Caudata, and revealed considerable interspecific differences in the length of respiratory capillaries per gram of body weight. This length was least in Amphiuma means (3.412 m to 3.753 m) and Siren intermedia (4.305 m), and greatest in Diemictylus viridescens (17.325 m). It was shown to be in an inverse relation to the size of the specimens of a species. The surface area of the respiratory capillaries varies widely, from 2.257 cm2/g in S. intermedia to over 8 cm2/g in D. viridescens and a small specimen of Taricha granulosa. In S. intermedia and A. means most of the respiratory capillaries are in the lungs (58.16 per cent and 68.20 per cent), and in the other species in the skin (87.50 per cent for Rhyacotriton olympicus to 54.04 per cent for Dicamptodon ensatus). The capillaries of the mouth account for only as small a proportion of all respiratory capillaries as 0.50 per cent in A. means to 6.40 per cent in a 4.50 g specimen of Ambystoma opacum.