In the light of the new knowledge various plausible, but frequently unsatisfying, suggestions put forward, especially by Wallace, Weismann, and their… - William Bateson

The concept of evolution as proceeding through the gradual transformation of masses of individuals by the accumulation of impalpable changes is one that the study of genetics shows immediately to be false. Once for all, that burden so gratuitously undertaken in ignorance of generic physiology by the evolutionists of the last century may be cast into oblivion. For the facts of heredity and variation unite to prove that genetic variation is a phenomenon of individuals.

I am well aware that some very eminent systematists regard the whole problem as solved. They hold as Darwin did that specific diversity has no physiological foundation or causation apart from adaptation, and that species are impermanent groups, the delimitations of which are ultimately determined by environmental exigency or "fitness." The specific diversity of living things is thus regarded as being something quite different in nature from the specific diversity of inorganic substances. In practice those who share these opinions are, as might be anticipated, to be found among the 'lumpers' rather than among the 'splitters.' In their work, certainly, the Darwinian theory is actually followed as a guiding principle; unanalysed intergradations of all kinds are accepted as impugning the integrity of species; the underlying physiological problem is forgotten, and while the product is almost valueless as a contribution to biological research, I can scarcely suppose that it aids greatly in the advances of other branches of our science.

If species had really arisen by the natural selection for impalpable differences, intermediate forms should abound, and the limits between species should be on the whole indefinite. As this conclusion follows necessarily from the premisses, the selectionists believe and declare that it represents the facts of nature. Difference between species being by axiom indefinite, the differences between varieties must be supposed to be still less definite. Consequently the conclusion that evolution must proceed by insensible transformation of masses of individuals has become an established dogma.