INDEPENDENCE OF POST-FERTILIZATION RESPIRATION IN THE SEA-URCHIN EGG FROM THE LEVEL OF RESPIRATION BEFORE FERTILIZATION

¹ Wenner-Gren's Institute for Experimental Biology, University of Stockholm

Using Cartesian diver micro-respiration technique, it was found that in Psammechinus miliaris the rate of respiration of the newly fertilized egg is independent of the rate of respiration of the unfertilized egg at the moment of fertilization.

The quotient (respiration after fertilization)/(respiration before fertilization) was found to decrease considerably(probably even to values < 1.0) if the time interval between egg removal from the ovary and fertilization was diminished. If the decreasing part of pre-fertilization respiration is given time to disappear before fertilization, the quotient lies between 3 and 4.

It is thought possible that the decreasing respiration part of the unfertilized egg is abolished upon fertilization, due to probable changes in the function of members of the oxidizing system, situated between the oxidase and the dehydrogenases. It cannot be decided from the experiments whether the constant respiration part of the unfertilized egg still participates in the respiration of the fertilized egg or not.