Comparatively few, then, though the facts may be of which I have given some examples, in my opinion they are amply sufficient for the purpose in hand. This purpose is to show that the question which we are now considering is very far from being a closed question; and, therefore, that the school of Weismann is much too precipitate in alleging that there is neither any necessity for, nor evidence of, the so-called Lamarckian factors[85]. And this opinion, whatever it may be worth, is at all events both deliberate and impartial. As one of the first to doubt the transmission of acquired characters, and as one who has spent many years in experimental inquiries upon the subject, any bias that I may have is assuredly against the Lamarckian principles--seeing that nearly all my experiments have yielded negative results. It was Darwin himself who checked this bias. But if the ultra-Darwinians of the last ten years had succeeded in showing that Darwin was mistaken, I should be extremely glad to fall into line with them. As already shown, however, they have in no way affected this question as it was left by Galton in 1875. And if it be supposed a matter of but little importance whether we agree with Galton in largely diminishing the comparative potency of the Lamarckian principles, or whether we agree with Weismann in abolishing them together, it cannot be too often repeated that such is an entirely erroneous view. No matter how faintly or how fitfully acquired characters may be transmitted, in so far as they are likewise adaptive characters, their transmission (and therefore their development) must be cumulative. Hence, the only effect of attenuating our estimate of their _intensity_, is that of increasing our estimate of their _duration_--i.e. of the time over which they have to operate in order to produce important results. And, even so, it is to be remembered that the importance of such results is not to be estimated by the magnitude of modification. Far more is it to be estimated by the character of modification as adaptive. For if functionally produced changes, and changes produced in adaptive response to the environment, are ever transmitted in a cumulative manner, a time must sooner or later arrive when they will reach a selective value in the struggle for existence--when, of course, they will be rapidly augmented by natural selection. Thus, if in any degree operative at all, the great function of these principles must be that of supplying to natural selection those incipient stages of adaptive modifications in all cases where, but for their agency, there would have been nothing of the kind to select. Themselves in no way dependent on adaptive modifications having already attained a selective value, these Lamarckian principles are (under the Darwinian theory) direct causes of determinate variation in adaptive lines; and variation in those lines being cumulative, the result is that