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.

    80/264 (page 76)
    formulas that serve to describe the activity of a machine will not suffice for living creatures which demand an historical explanation. When we leave the chemical and physical standpoint, and look at the living creature as biologists, we recognize four chief character¬ istics—growth, cyclical development, effective response, and unified behaviour. The living creature grows after a fashion all its own, not as a rolling snowball, by mere accretion, but by a unifying incorporation; not even as a crystal grows, at the expense of dissolved material chemically the same as itself, but at the expense of material different from itself. Again, it has a cyclical development, from egg-cell to seedling, from seedling to bean¬ stalk; from egg-cell to tadpole, from tadpole to frog; it shows an orderly, correlated, regu¬ lated succession of events, which leads from apparent simplicity to obvious complexity; but, as Huxley puts it, “ no sooner has the edifice, reared with such exact elaboration, attained completeness, than it begins to crumble.” Inanimate objects have a certain power of response to external stimuli, as a piece of potassium shows when thrown on a basin of water, but the responses of a living creature in normal surroundings are effective, self-preservative, usually making for better-