Delayed Implantation

Abstract

In 1935 Hamlett attempted to review all that was known at that time of the patterns of delayed implantation, and he assessed the suggestions previously published as to its ecological importance. He noted no common ecological factors and suggested that delayed implantation was a relatively useless characteristic, in which the hormonal situation governing the delay may have become closely associated with some other unknown characteristic which was of evolutionary importance. There is now available considerably more information on the patterns and taxonomic distribution of this phenomenon, but basically Hamlett’s observation of a lack of common ecological relationships still holds good.