Water Absorption in the Egg Sac of the Salamander Hynobius nigrescens

Abstract

Relationships between days after insemination and changes in mass, inner layer length, and outer and inner layer widths of egg sacs associated with the absorption of water were examined in Hynobius nigrescens. Egg sac mass, which exhibited a continuous increase irrespective of water temperature until hatching, was the best parameter for estimating dates of oviposition. A regression equation for this purpose is presented by applying the analysis of analogue and digital data.