E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Darwins theory is that different forms of animal and vegetable life are due to small variations, and that natural selection is a main agent in bringing them about. If favourable, these variations are perpetuated, if not they die off.
Spencers theory is that the present multitude of objects have all sprung from separate atoms originally homogeneous.
Evolution is the integration of matter and concomitant dissipation of motion, during which the matter passes from an indefinite, incoherent homogeneity to a definite coherent heterogeneity; and during which the retained motion undergoes a parallel transformation.Spencer: First Principles, part ii. chap. xvii. p. 396.