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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    theory, and believe that the giraffe lengthened its neck by stretching it; yet we must be¬ ware of taking too simple a view of what function implies. What are the certainties ? We know that development—the expression of an inheritance—demands functional as well as environmental stimuli. Practice makes an organ possible. Without exercise it will not develop fully. Again, we know that changes in function have great individual importance. By force of smiting one be¬ comes a smith. Even if there be no multi¬ plication of muscle-fibres after the more strenuous function began, each fibre is larger and worth more. Contrariwise, disuse means deterioration; when we rest too much we rust. No one has ever doubted the individual im¬ portance of functional modifications. Further, although the transmission of a functional modification remains unproved, the secondary and indirect results may influence the germ- cells and the offspring. It is idle to say that what living creatures do or fail to do has no racial importance. Another certainty is that by its activity a living creature, being no mere puppet of fate, may alter the whole situation. This, again, may have evolu¬ tionary interest, even if it ends fatally. Admitting all this, can we say more ?