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LIST OF ILLUSTRATIONS

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PortraIT OF AUTHOR

. . . Frontispiece MAP SHOWING THE 1000-FATHOM LINE . . To face page 349 FIG. : 1. DIAGRAM OF VARIATIONS OF LACERTA MURALIS . . 47

VARIATION OF LIZARDS . .
VARIATION OF WINGS AND TAIL OF BIRDS
VARIATION OF DOLICHONYX ORYZIVORUS
VARIATION OF AGELEUS PHỌNICEUS . . 56
VARIATION OF CARDINALIS VIRGINIANUS
VARIATION OF TARSUS AND TOES
VARIATION OF BIRDS IN LEYDEN MUSEUM
VARIATION OF ICTERUS BALTIMORE
VARIATION OF AGELÆUS PHENICEUS
CURVES OF VARIATION :
VARIATION OF CARDINALIS VIRGINIANUS
VARIATION OF SCIURUS CAROLINENSIS.
VARIATION OF SKULLS OF WOLF
VARIATION OF SKULLS OF URSUS LABIATUS : 72

VARIATION OF SKULLS OF SUS CRISTATUS : 73 17. PRIMULA VERIS (Cowslip). From Darwin's Forms of Flowers . 157 18. GAZELLA SEMMERRINGI (to show recognition marks) . . 219 19. RECOGNITION MARKS OF AFRICAN PLOVERS (from Seebohm's

Charadriado . . . . . . . 221

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FIG.
20. RECOGNITION OF EDICNEMUS VERMICULATUS AND E. SENEGA-

LENSIS (from Seebohm's Charadriado) . . . 223 21. RECOGNITION OF CURSORIUS CHALCOPTERUS AND C. GALLICUS

(from Seebohm's Charadriada) . . . . 224 22. RECOGNITION OF SCOLOPAX MEGALA AND S. STENURA (from

Seebohm's Charadriadce) . . . . . 225 23. METHIONA PSIDII AND LEPTALIS ORISE.

. . 241 24. OPTHALMIS LINCEA AND ARTAXA SIMULANS (from the Official

Narrative of the Voyage of the Challenger) . . . 247 25. Wings of ITUNA ILIONE AND THYRIDIA MEGISTO (from Pro

ceedings of the Entomological Society) . . . . 251 26. MYGNIMIA AVICULUS AND COLOBORHOMBU'S 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-BIND 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 Palaobotany). . . 402 35. TRANSFORMATION OF ARTEMIA SALINA TO A. MILHAUSENI

(from Semper's Animal Life). . . . . 426 36. BRANCHIPUS STAGNALIS AND ARTEMIA SALINA (from Semper's Animal Life) .

. . 427 37. CHIMPANZEE (TROGLODYTES NIGER)

. 454

CHAPTER I

WHAT ARE “SPECIES,” AND WHAT IS MEANT BY

THEIR “ORIGIN

Definition of species-Special creation—The early Transmutationists

Scientific opinion before Darwin—The problem before DarwinThe change of opinion effected by Darwin-The Darwinian theory -Proposed mode of treatment of the subject.

THE title of Mr. Darwin's great work is—On the Origin of Species by means of Natural Selection and the Preservation of Favoured Races in the Struggle for Life. In order to appreciate fully the aim and object of this work, and the change which it has effected not only in natural history but in many other sciences, it is necessary to form a clear conception of the meaning of the term "species,” to know what was the general belief regarding them at the time when Mr. Darwin's book first appeared, and to understand what he meant, and what was generally meant, by discovering their “ origin.” It is for want of this preliminary knowledge that the majority of educated persons who are not naturalists are so ready to accept the innumerable objections, criticisms, and difficulties of its opponents as proofs that the Darwinian theory is unsound, while it also renders them unable to appreciate, or even to comprehend, the vast change which that theory has effected in the whole mass of thought and opinion on the great question of evolution.

The term “species ” was thus defined by the celebrated botanist De Candolle : “A species is a collection of all the individuals which resemble each other more than they resemble anything else, which can by mutual fecundation

is for wantenerally meant, understand when Mr.

B

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