The dominance of maternal or of paternal characters in Echinoderm hybrids

Abstract

1) The crossHipponoE ♂/Toxopneustes ♀ and the reciprocal crossToxopneustes ♂/HipponoE ♀ were easily made after allowing the eggs to stand in sea water for some hours before fertilization. 2) In the embryos of both crosses made in ordinary sea water, which was alkaline, theHipponoE influence showed a tendency to predominate. 3) In the embryos of both crosses made in sea water of increased alkalinity, there was evidence of an increase ofHipponoE influence. 4) In the embryos of both crosses made in sea water of decreased alkalinity, a tendency towardToxopneustes dominance was evident. 5) The results thus showHipponoE dominance in sea water of a higher OH ion concentration andToxopneustes dominance in sea water of a lower OH ion concentration. 6) I suggest that these variations in the alkalinity of the sea water, brought about artificially, may correspond to normal seasonal changes. 7) If this be true, the winter (paternal) embryos and the summer (maternal) plutei of the combinationStrongylocentrotus ♂/Sphaerechinus ♀ of other investigators, had their origin in such normal seasonal changes of OH ion concentration. 8) The results of the investigation suggest specific tendencies toward different grades of alkalinity.