Habit and instinct / by C. Lloyd Morgan.

  • C. Lloyd Morgan
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: Habit and instinct / by C. Lloyd Morgan. Source: Wellcome Collection.

    334/402 page 320
    8. Suppose, however, that a group of plastic organ- isms is placed under new conditions. 9. Those whose innate plasticity is equal to the occa- sion are modified, and survive. Those whose plasticity is not equal to the occasion are eliminated. 10. Such modification takes place generation after generation, hut, as such, is not inherited. There is no transmission of the effects of modification to the germinal substance. 11. But variations in the same direction as the modi- fications, are now no longer repressed and are allowed full scope. 12. Any congenital variations antagonistic in direction to these modifications will tend to thwart them and to render the organism in which they occur liable to elimination. 18. Any congenital variations similar in direction to these modifications will tend to support them and to favour the organism in which they occur. 14. Thus will arise a congenital predisposition to the modifications in question. 15. The longer this process continues, the more marked will be the predisposition, and the greater the tendency of the congenital variations to conform in all respects to the persistent plastic modifications ; while 16. The plasticity still continuing, the modifications become yet further adaptive. 17. Thus plastic modification leads, and germinal variation follows: the one paves the way for the other. 18. Natural selection will tend to foster variability in given advantageous lines when once initiated; for (a) the constant elimination of variations leads to the survival of the relatively invariable; but (b) the perpetuation of variations in any given direction leads to the survival of
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