Bidirectional movement of water through the skin of a nonsweating animal.

Abstract Exchange of water between body fluids and a saturated atmosphere was measured in dogs using D 2 O as the tracer. Bidirectional transfer rates were calculated from a series of eight experiments in which the tracer was placed first in the chamber. Outward diffusion of D 2 O averaged 32.5 ± 5.9 (S.D.) gm. per square meter per hour and inward 26 ± 13.4 gm. per square meter per hour. Outward transfer was calculated from a second series of nine experiments in which the D 2 O was injected intravenously into the dog and averaged in this series 34.5 ± 15.5 gm. per square meter per hour. Mean water loss through the skin of these nonsweating animals was greater than absorption even in a saturated atmosphere.