INDEX

A.

Accident, Darwin's use of the word, 334-340;
beauty due to, 408, 409.

Achromatin, 126-134.

Acquired characters, _see_ Characters.

_Acraea eurita_, 328.

Adaptation, facts of, in relation to theory of natural selection,
401-403, 411.

Adaptive characters, _see_ Characters.

AEsthetic sense in animals, 380-385;
_see_ Beautiful.

Agassiz, Prof. A., on fauna of the Mammoth cave, 70.

Alpine plants, 209, 210, 440-442.

_Amauris niavius_, 328.

_Amblyornis inornata_, 381-383.

_Amphioxus_, 137, 138, 145, 146.

Analogy, 38, 50-65, 176, 177, 347-350.

Anthropoid, _see_ Apes.

Antlers, 98-100, 167-169.

Ants, co-operative instincts of, 268;
leaf-cutting, 332;
keeping aphides, 292.

Ape, eye of, 75;
_appendix vermiformis_ of, 84-86.

Apes, ears of, compared with those of man, 88;
muscles of, 77, 82, 83;
feet of, 77, 78;
tail of, compared with that of man, 82-84;
hair of, compared with that of man, 89-91;
teeth of, compared with those of man, 92-94;
flattening of tibiae of, 95, 96.

Aphides, 292.

_Appendix vermiformis_ of man compared with that of orang, 84-86.

_Apteryx_, 68, 69.

_Archaeopteryx_, 171-173.

Arctic plants, 209, 210, 440-442.

Argyll, Duke of, on natural selection, 334-362.

Aristotle, his idea of scientific method, 1;
on classification, 23, 24.

Arm, distribution of hair on, in man and apes, 89-92.

_Arthropoda_, embryology of, 155.

Artificial selection, analogy of, to natural selection, 295-314;
pictorial representations of products of, 298-312.

Artiodactyls, 182-191.

Association, principle of, in aesthetics, 404-407.

Aster, 129-133.

Attraction-spheres, 128, 132, 133.

Australia, fauna of, 204, 205;
thriving of exotic species in, 286;
portrait of wild dog of, 304.

Azores, 224, 225.

B.

Bacon, Lord, on scientific method, 2.

_Balanoglossus_, 147, 148.

_Baptanodon discus_, posterior limb of, 179-181.

Barriers, in relation to geographical distribution, 216-224.

Bats, 56, 224, 226, 240.

Battle, law of, 385, 386.

Baya-bird, 381.

Bear, skeleton of, 174;
feet of, 178.

Beautiful, the, sense of, in animals, 380-385;
standards of, 380-404;
Darwin's explanation of, in organic nature, 379-411;
facts of, in inorganic nature in relation to Darwin's theory of, in
organic, 404;
often determined by natural selection, 406, 407;
absent in many plants and animals, 408