Plasticity in Darwin's Origin of the Species 6th Edition

Historical Sketch

Plasticity xv - He extends the same view to animals. The Dean {Hon. and Rev. W Herbert} believes that single species of each genus were created in an originally highly plastic condition, and that these have produced, chiefly by intercrossing, but likewise by variation, all our existing species.

Finality error xix - He {M Naudin} believes, like Dean Herbert, that species, when nascent , were more plastic than at present. He lays weight on what he calls the principle of finality.

The Origin

9 Any variation which is not inherited is unimportant for us. But the number and diversity of inheritable deviations of structure, both those of slight and those of considerable physiological importance, are endless.

22 The great power of this principle of selection is not hypothetical. It is certain that several of our eminent breeders have, even within a single lifetime, modified to a large extent their breeds of cattle and sheep.

62 Under domestication, it may truly be said that the whole organism becomes in some degee plastic.

106 The direct action of changed conditions leads to definite or indefinite results. In the later case the organism seems to become plastic and we have much fluctuating variability.

385 He {E Ray Lankester} proposes to call the structures which resemble each other in distinct animals, owing to their descent from a common progenitor with subsequence modifications homogeneous; and the resemblances which cannot this be accounted for, he proposes to call homoplastic.

Glossary 438 Plastic - Readilly capable of change.