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.

    146/264 (page 142)
    There are variations which mean aug¬ mentation, or diminution, or re-arrangement of already existing qualities. Now, if the hereditary qualities are carried by represent¬ ative particles in the germ-cells, we can in a measure understand the origin of the kind of variation referred to; for extraordinarily intricate permutations and combinations go on in the microcosm of the germ-cells. Particularly in the process of maturation is there what we might call a shuffling of the cards—even a throwing away of half of the pack. In fertilization, again, paternal and maternal contributions form a new unity. Perhaps there may be, as Weismann supposes, a struggle between rival hereditary items. But there seems to be another kind of variation, qualitative rather than quantita¬ tive, substantive rather than architectural, when something distinctively new appears. What can be said as to their origin ? Weis¬ mann has suggested that the oscillations and changes in the blood and other nutritive fluids may stimulate the germ-plasm to a new departure. It may also be that important changes in the environment may saturate through the body and provoke the germ- plasm to vary. There are other 66 may be’s.” With all recognition and appreciation of