Page:The British Warblers A History with Problems of Their Lives - 9 of 9.djvu/58

 appeal to the biological transmission of acquired modification with little or no evidence to go upon? It is here that Professor Lloyd Morgan's principle of the "survival of coincident variations" comes to our aid; and to one who sees—needlessly perhaps—in the psychological aspect of the evolution of behaviour difficulties of interpretation on any known naturalistic hypothesis, acquired modification as the foster-parent of congenital variation seems to be a step in the right direction. I believe it to be an important principle, removing as it does in some measure the difficulties which surround the survival value of incipient variations.