"growth-force", "bathmism", "self-adaptation", etc. Some of the terms employed have a teleological (illegible text)view about them. They recall to our minds those expressions concerning an "inherent tendency towards progression" which are found in the writings of the older naturalists and philosophers as far back even as Aristotle. The writers belonging to this school are evidently striving to give utterance to some ideas which they have in their minds but which they have not yet succeeded in putting in clear and unambiguous terms; the expressions used are but approximations towardsto words whichwhat they want to convey. They seem to be groping after some as yet undiscovered law or laws of growth and development.
From all this it is evident that the problem of the origin of species is as yet far from being solved. Biologists are now busily engaged in pushing their enquiries further back than was done by Darwin. Variations must be present for natural selection to work upon, so there is something to explain before natural selection can begin its work. This was admitted by Darwin himself: in his Animals and Plants under Domestication (2nd.Ed. Vol.l., p.277) he says "Natural Selection has no relation whatever to the primary cause of any modification of structure". He took the variations which are found to occur in nature as his starting-point. Regarding the causes of variation he tells us repeatedly that he is profoundly ignorant, and nowhere in his works do we find any attempt to explain them.
