CHAPTER IX

WARNING COLORATION AND MIMICRY

The skunk as an example of warning coloration-Warning colours among

insects-Butterflies-Caterpillars-Mimicry-How mimicry has been

produced-Heliconidæ — Perfection of the imitation—Other cases of

mimicry among Lepidoptera-Mimicry among protected groups—Its

explanation-Extension of the principle-Mimicry in other orders of

insects-Mimicry among the vertebrata-Snakes-The rattlesnake and

the cobra--Mimicry among birds-Objections to the theory of mimicry

-Concluding remarks on warning colours and mimicry

Pages 232-267

CHAPTER X

COLOURS AND ORNAMENTS CHARACTERISTIC OF SEX

Sex colours in the mollusca and crustacea-In insects-In butterflies and

moths-Probable causes of these colours-Sexual selection as a

supposed cause-Sexual coloration of birds-Cause of dull colours of

female birds-Relation of sex colour to nesting habits-Sexual colours

of other vertebrates-Sexual selection by the struggles of males—

Sexual characters due to natural selection-Decorative plumage of

males and its effect on the females-Display of decorative plumage

by the males—A theory of animal coloration—The origin of accessory

plumes-Development of accessory plumes and their display--The

effect of female preference will be neutralised by natural selection--

General laws of animal coloration-Concluding remarks . 268-300

CHAPTER XI

THE SPECIAL COLOURS OF PLANTS: THEIR ORIGIN

AND PURPOSE

The general colour relations of plants-Colours of fruits-The meaning of

nuts-Edible or attractive fruits-The colours of flowers-Modes of

securing cross-fertilisation-The interpretation of the facts-Summary

of additional facts bearing on insect fertilisation-Fertilisation of

flowers by birds-Self-fertilisation of flowers-Difficulties and con-

tradictions-Intercrossing not necessarily advantageous-Supposed

evil results of close interbreeding-How the struggle for existence

acts among flowers-Flowers the product of insect agency-Concluding

remarks on colour in nature

Pages 301-337

CHAPTER XII

THE GEOGRAPHICAL DISTRIBUTION OF ORGANISMS

The facts to be explained-The conditions which have determined dis-

tribution-The permanence of oceans-Oceanic and continental areas

-Madagascar and New Zealand-The teachings of the thousand-

fathom line-The distribution of marsupials-The distribution of

tapirs-Powers of dispersal as illustrated by insular organisms-Birds

and insects at sea—Insects at great altitudes-The dispersal of plants

-Dispersal of seeds by the wind-Mineral matter carried by the wind

---Objections to the theory of wind-dispersal answered-Explanation

of north temperate plants in the southern hemisphere-No proof of

glaciation in the tropics-Lower temperature not needed to explain

the facts-Concluding remarks

338-374

CHAPTER XIII

THE GEOLOGICAL EVIDENCES OF EVOLUTION

What we may expect-The number of known species of extinct animals-

Causes of the imperfection of the geological record-Geological

evidences of evolution-Shells-Crocodiles-The rhinoceros tribe-

The pedigree of the horse tribe-Development of deer's horns-Brain

development-Local relations of fossil and living animals-Cause

of extinction of large animals-Indications of general progress in

plants and animals-The progressive development of plants-Possible

cause of sudden late appearance of exogens-Geological distribu-

tion of insects-Geological succession of vertebrata - Concluding

remarks

375-409

CHAPTER XIV

FUNDAMENTAL PROBLEMS IN RELATION TO VARIATION

AND HEREDITY

Fundamental difficulties and objections--Mr. Herbert Spencer's factors

of organic evolution-Disuse and effects of withdrawal of naturål

selection-Supposed effects of disuse among wild animals-Difficulty

as to co-adaptation of parts by variation and selection--Direct action

of the environment-The American school of evolutionists--Origin

of the feet of the ungulates-Supposed action of animal intelligence—

Semper on the direct influence of the environment-Professor Geddes's

theory of variation in plants-Objections to the theory-On the

origin of spines-Variation and selection overpower the effects of use

and disuse-Supposed action of the environment in imitating varia-

tions-Weismann's theory of heredity—The cause of variation-The

non-heredity of acquired characters-The theory of instinct-Con-

cluding remarks

Pages 410-444

CHAPTER XV

DARWINISM APPLIED TO MAN

General identity of human and animal structure-Rudiments and varia-

tions showing relation of man to other mammals-The embryonic

development of man and other mammalia-Diseases common to man

and the lower animals-The animals most nearly allied to man-

The brains of man and apes-External differences of man and apes—

Summary of the animal characteristics of man-The geological

antiquity of man—The probable birthplace of man-The origin of

the moral and intellectual nature of man-The argument from

continuity-The origin of the mathematical faculty-The origin of

the musical and artistic faculties-Independent proof that these

faculties have not been developed by natural selection-The inter-

pretation of the facts-Concluding remarks

445-478

17. PRIMULA VERIS (Cowslip). From Darwin's Forms of Flowers. 157

18. GAZELLA SOMMERRINGI (to show recognition marks)

219

19. RECOGNITION MARKS OF AFRICAN PLOVERS (from Seebohm's

Charadriada

221

FIG.

PAGE

20. RECOGNITION OF EDICNEMUS VERMICULATUS AND E. SENEGALENSIS (from Seebohm's Charadriada)

223

21. RECOGNITION OF CURSORIUS CHALCOPTERUS AND C. GALLICUS (from Seebohm's Charadriadœ)

224

22. RECOGNITION OF SCOLOPAX MEGALA AND S. STENURA (from Seebohm's Charadriada)

225

241

23. METHONA PSIDII AND LEPTALIS ORISE.

24. OPTHALMIS LINCEA AND ARTAXA SIMULANS (from the Official Narrative of the Voyage of the Challenger)

25. WINGS OF ITUNA ILIONE AND THYRIDIA MEGISTO (from Proceedings of the Entomological Society) .

247

251

26. MYGNIMIA AVICULUS AND COLOBORHOMBUS FASCIATIPENNIS 259 27. MIMICKING INSECTS FROM THE PHILIPPINES (from Semper's Animal Life)

260

28. MALVA SYLVESTRIS AND M. ROTUNDIFOLIA (from Lubbock's British Wild Flowers in Relation to Insects) .

311

29. LYTHRUM SALICARIA, THREE FORMS OF (from Lubbock's British Wild Flowers in Relation to Insects)

312

30. ORCHIS PYRAMIDALIS (from Darwin's Fertilisation of Orchids). 314 31. HUMMING-BIRD FERTILISING MARCGRAVIA NEPENTHOIDES 320

32. DIAGRAM OF MEAN HEIGHT OF LAND AND DEPTH OF OCEANS 345 33. GEOLOGICAL DEVELOPMENT OF THE HORSE TRIBE (from Huxley's American Addresses)

388

34. DIAGRAM ILLUSTRATING THE GEOLOGICAL DISTRIBUTION OF PLANTS (from Ward's Sketch of Palæobotany).

402

35. TRANSFORMATION OF ARTEMIA SALINA TO A. MILHAUSENII (from Semper's Animal Life).

36. BRANCHIPUS STAGNALIS AND ARTEMIA SALINA (from Semper's

Animal Life).

37. CHIMPANZEE (TROGLODYTES NIGER)

426

427

454