The new heredity, to characterize by this term the extraordinary increase and the more exact kind of knowledge of heredity acquired since the first recognition, in 1900, of Mendelism, has so shattered the seemingly unassailable logical structure of the natural selection explanation of evolution that it stands now only as a tottering skeleton of its once imposing self. It had always too much assumption of premises for its foundation and too much logic and finespun theory in its superstructure to be an enduring building. Even before the new knowledge of the facts and mechanism of heredity was available natural selection was already weakening under the criticism of scientific men, although but little of this was known to the man in the street. And even now when the new heredity has furnished the knowledge for a complete undermining of the natural selection theory as a species-forming factor, only occasional rumors of the disaster find their way into popular literature. But long ago there began a popular revolt against the conception of the whole world of nature and man as ruled by a theory of continuous ruthless bloody struggle. Everyone knew that this was not the only relation of human beings to each other, and even most casual observation indicated that it was not the only relation of various kinds of the lower animals to each other. The obvious biological success of the social or communal insects, the numerous instances of commensalism, or the living together on terms of mutual advantage of individuals of different species--the various ants alone have more than a thousand known kinds of other insects living with them--and the innumerable observed instances of what might be called balanced adaptations, such as those of the flower-visiting insects and the insect-visited flowers resulting in the needed cross-fertilization of the flowers and the needed supply of nectar and pollen food for the insects--all these had convinced biologists and nature-students and just nature-lovers that _if_ natural selection were the all-ruling factor in determining the present character and the future of the living world it was a very different natural selection from that so redly painted by the Neo-Darwinians.