Prometheus, or, biology and the advancement of man / by H.S. Jennings.

  • Herbert Spencer Jennings
Date:
[1925]
Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Prometheus, or, biology and the advancement of man / by H.S. Jennings. Source: Wellcome Collection.

    61/112 (page 57)
    BIOLOGICAL BACKGROUND the eyes and the stature, lies in certain practical diificulties, not in any differ¬ ence of principle. In the group of organisms to which man belongs there is an early period in which it is practic¬ ally difficult to change effectively the conditions under which the organism develops, because it is enclosed within the mother's body, or within a resistant egg shell. So we have gotten accustomed to calling inherited those characteristics which are determined before it leaves its mother's body or the egg, while those determined later are called acquired characters. But this is an artificial distinction, based on practical considerations. In many organisms there is no such distinction into two periods ; in them it is possible to alter the conditions at any period, even the earliest. And when this is done it is [59]