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12 Again he has been forced by the accumulation of evidence from many quarters to modify somewhat his views concerning the influence of environmental changes on the germ-plasm. He admits that the germ-plasm may be affected by change in environment, and  he has even allowed that changes of climate and nutrition may act through the body on the germ, not to produce  in the next generation, but as stimuli causing some amount of variation.

While Weismann's theory of heredity shuts out altogether any possibility of the Lamarckian factors having played a part in the origin or species among the Metazoa, a theory had been formulated by Galton some years previously (187) which was also based on the idea or the continuity of the material basis of heredity but which did not exclude the possibility of the substance being modified to some extent occasionally by the somatic tissues. And as pointed out by Romanes (Darwin and after Darwin, Vol II.p.47) the Lamarckian factors even if admitted to a slight degree must have had an enormous influence in determining the course of organic evolution; "seeing that their action in any degree must always have been of variation on the one hand, and  on the other.

It is now recognised that the problems of Heredity and that of the transmissibility of acquired characters are not to be settled by hypothetical speculations. The appeal must be made to facts - the accumulation of observations and the