"Since the belief in transmission of acquired adaptations arose from preconception rather than from evidence, it is worth observing that, rightly considered, the probability should surely be the other way. For the adaptations relate to every variety of exigency. To supply themselves with food, to find it, to seize and digest it, to protect themselves from predatory enemies whether by offence or defence, to counter-balance the changes of temperature, or pressure, to provide for mechanical strains, to obtain immunity from poison and from invading organisms, to bring the sexual elements into contact, to ensure the distribution of the type; all these and many more are accomplished by organisms in a thousand most diverse and alternative methods. Those are the things that are hard to imagine as produced by any concatenation of natural events; but the suggestions that organisms had had from the beginning innate in them a power of modifying themselves, their organs and their instincts so as to meet these multifarious requirements does not materially differ from the more overt appeals to supernatural intervention. The conception, originally introduced by Hering and independently by S. Butler, that adaptation is a consequence or product of accumulated memory was of late revived by Semon and has been received with some approval, especially by F. Darwin. I see nothing fantastic in the notion that memory may be unconsciously preserved with the same continuity that the protoplasmic basis of life possesses. That idea, though purely speculative and, as yet, incapable of proof or disproof contains nothing which our experience of matter or of life at all refutes. On the contrary, we probably do well to retain the suggestion as a clue that may some day be of service. But if adaptation is to be the product of these accumulated experiences, they must in some way be translated into terms of physiological and structural change, a process frankly inconceivable."

“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.”

“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.”

“I well remember receiving from one of the most earnest of my seniors the friendly warning that it was waste of time to study variation, for "Darwin had swept the field." Parenthetically we may notice that though scientific opinion in general became rapidly converted to the doctrine of pure selection, there was one remarkable exception. Systematists for the most part kept aloof. Everyone was convinced that natural selection operating in a continuously varying population was a sufficient account of the origin of species except the one class of scientific workers whose labours familiarised them with the phenomenon of specific difference. From that time the systematists became, as they still in great measure remain, a class apart.”

“Misconception was especially brought in by describing descent in terms of "blood". The common speech uses expressions such as consanguinity, pure-blooded, half-blood, and the like, which call up a misleading picture to the mind. Blood is in some respects a fluid, and thus it is supposed that this fluid can be both quantitatively and qualitatively diluted with other bloods, just as treacle can be diluted with water.”

“In the light of the new knowledge various plausible, but frequently unsatisfying, suggestions put forward, especially by Wallace, Weismann, and their followers, as probable accounts of evolutionary progress, must be finally abandoned.”

“That the variations are controlled by physiological law, we have now experimental proof; but that this control is guided ever so little in response to the needs of adaptation there is not the smallest sign.”