Evolution / by Patrick Geddes and J. Arthur Thomson.

  • Patrick Geddes
Date:
[1911?]
Catalogue details

Licence: Public Domain Mark

Credit: Evolution / by Patrick Geddes and J. Arthur Thomson. Source: Wellcome Collection.

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    be readily sifted out from the slumped total. Others may be wrapped up with age, and these can also be analyzed out. Others are due to something unusual in the 44 nurture ” in the wide sense; that is, they are the direct results of peculiarities in surrounding influ¬ ences and of peculiarities of habit. Such changes in the bodies of plants and animals are extrinsic, not intrinsic, in origin; they are acquired, not inborn. They are technically called 44 acquired characters,” or much more clearly 44 modifications.” They may be de¬ fined as structural changes in a part of the body, directly induced by peculiarities of use or disuse, or by some change in surroundings and nurture generally, which transcend the limit of organic elasticity and thus persist after the inducing conditions have ceased to operate. No convincing evidence of their transmission has as yet been forthcoming. Now the point is that when we subtract from the total of observed differences all that can be regarded as individual modifications, we have a very interesting remainder, which we thus define off as inborn or germinal variations. They are intrinsic, not extrinsic; inborn, not made. We cannot causally relate them in a direct way to peculiarities in habits or surroundings; they are often distinct at