SOME FEMALE COORDINATING FACTORS IN AMPHIBIAN FERTILIZATION

The influence of volume and ionic composition of the hydrating media upon the fertility of Bufo arenarum oocyte strings, has been studied with the following results: a) when immersed in equal volumes of ionic and non-ionic media, oocyte strings have been found to become more hydrated in the latter ones; b) oocytes are no longer fertile when hydration is 300-400% of their original weight (critical hydration). Fertility is recovered by adding ions or egg water to the medium or by modifying its pH; c) when hydration is beyond 500% of the original string weight (extensive hydration) fertility can also be recovered by these treatments, but only after a partial jelly-coat liquefaction by thioglycolate. Egg water was also studied, and shown to have a buffering capacity between pH 5.5 and 7.0. It seems not to influence acrosomic proteinase release.