NEWLY-ACQUIRED CHARACTERS IN OUR DOMESTICATED

ANIMALS

OFTEN TRANSMITTED BY ONE SEX ALONE, SOMETIMES LOST BY ONE

SEX ALONE-INHERITANCE AT CORRESPONDING PERIODS OF LIFE-

THE IMPORTANCE OF THE PRINCIPLE WITH RESPECT TO EMBRY-

OLOGY; AS EXHIBITED IN DOMESTICATED ANIMALS; AS EXHIBITED

IN THE APPEARANCE AND DISAPPEARANCE OF INHERITED DIS-

EASES; SOMETIMES SUPERVENING EARLIER IN THE CHILD THAN

IN THE PARENT-SUMMARY OF THE THREE PRECEDING CHAPTERS.

Pages 37-61

CHAPTER XV.

ON CROSSING.

FREE INTERCROSSING OBLITERATES THE DIFFERENCES BETWEEN ALLIED

BREEDS WHEN THE NUMBERS OF TWO COMMINGLING BREEDS ARE

UNEQUAL, ONE ABSORBS THE OTHER-THE RATE OF ABSORPTION

DETERMINED BY PREPOTENCY OF TRANSMISSION, BY THE CON-

DITIONS OF LIFE, AND BY NATURAL SELECTION-ALL ORGANIC

BEINGS OCCASIONALLY INTERCROSS ; APPARENT EXCEPTIONS-ON

CERTAIN CHARACTERS INCAPABLE OF FUSION; CHIEFLY OR EX-

CLUSIVELY THOSE WHICH HAVE SUDDENLY APPEARED IN THE IN-

DIVIDUAL-ON THE MODIFICATION OF OLD, RACES, AND THE

FORMATION OF NEW RACES, BY CROSSING-SOME CROSSED RACES

HAVE BRED TRUE FROM THEIR FIRST PRODUCTION-ON THE CROSS-

ING OF DISTINCT SPECIES IN RELATION TO THE FORMATION OF

DOMESTIC RACES
62-77

CHAPTER XVI.

CAUSES WHICH INTERFERE WITH THE FREE CROSSING OF

VARIETIES-INFLUENCE OF DOMESTICATION ON FER-

TILITY.

DIFFICULTIES IN JUDGING OF THE FERTILITY OF VARIETIES WHEN

CROSSED-VARIOUS CAUSES WHICH KEEP VARIETIES DISTINCT, AS

THE PERIOD OF BREEDING AND SEXUAL

PREFERENCE-VARIETIES

OF WHEAT SAID TO BE STERILE WHEN CROSSED-VARIETIES OF

MAIZE, VERBASCUM, HOLLYHOCK, GOURDS, MELONS, AND TOBACCO

120

RENDERED IN SOME DEGREE MUTUALLY STERILE-DOMESTICATION

ELIMINATES THE TENDENCY TO STERILITY NATURAL TO SPECIES

WHEN CROSSED-ON THE INCREASED FERTILITY OF UNCROSSED

ANIMALS AND PLANTS FROM DOMESTICATION AND CULTIVATION.

Pages 78-91

CHAPTER XVII.

ON THE GOOD EFFECTS OF CROSSING, AND ON THE EVIL

EFFECTS OF CLOSE INTERBREEDING.

DEFINITION OF CLOSE INTERBREEDING-AUGMENTATION OF MORBID

TENDENCIES-CENERAL EVIDENCE OF THE GOOD EFFECTS DERIVED

FROM CROSSING, AND ON THE EVIL EFFECTS OF CLOSE INTERBREED-

ING-CATTLE, CLOSELY INTERBRED; HALF-WILD CATTLE LONG

KEPT IN THE SAME PARKS-SHEEP-FALLOW-DEER-DOGS, RABBITS,

PIGS-MAN, ORIGIN OF HIS ABHORRENCE OF INCESTUOUS MARRIAGES

-FOWLS-PIGEONS -

-HIVE-BEES- PLANTS, GENERAL CONSIDERA-

TIONS ON THE BENEFITS DERIVED FROM CROSSING-MELONS, FRUIT-

TREES, PEAS, CABBAGES, WHEAT, AND FOREST-TREES-ON THE

INCREASED SIZE OF HYBRID PLANTS, NOT EXCLUSIVELY DUE TO

THEIR STERILITY-ON CERTAIN PLANTS WHICH EITHER NORMALLY

OR ABNORMALLY ARE SELF-IMPOTENT, BUT ARE FERTILE BOTH

ON THE MALE AND FEMALE SIDE, WHEN CROSSED WITH DISTINCT

INDIVIDUALS EITHER OF THE SAME OR ANOTHER SPECIES-CON-
CLUSION..

92-126

CHAPTER XVIII.

ON THE ADVANTAGES AND DISADVANTAGES OF CHANGED

CONDITIONS OF LIFE: STERILITY FROM VARIOUS CAUSES.

ON THE GOOD DERIVED FROM SLIGHT CHANGES IN THE CONDITIONS OF

LIFE-STERILITY FROM CHANGED CONDITIONS, IN ANIMALS, IN

THEIR NATIVE COUNTRY AND IN MENAGERIES-MAMMALS, BIRDS,

AND INSECTS-LOSS OF SECONDARY SEXUAL CHARACTERS AND OF

INSTINCTS-CAUSES OF STERILITY-STERILITY OF DOMESTICATED

ANIMALS FROM CHANGED CONDITIONS-SEXUAL INCOMPATIBILITY

OF INDIVIDUAL ANIMALS - STERILITY OF PLANTS FROM CHANGED

CONDITIONS OF LIFE-CONTABESCENCE

OF THE ANTHERS-MON-

STROSITIES AS A CAUSE OF STERILITY-DOUBLE FLOWERS-SEED-

LESS FRUIT-STERILITY FROM THE EXCESSIVE DEVELOPMENT OF

THE ORGANS OF VEGETATION-FROM LONG-CONTINUED PROPAGA-

TION BY BUDS-INCIPIENT STERILITY THE PRIMARY CAUSE OF

DOUBLE FLOWERS AND SEEDLESS FRUIT

Pages 127-156

CHAPTER XIX.

SUMMARY OF THE FOUR LAST CHAPTERS, WITH REMARKS

ON HYBRIDISM.

ON THE EFFECTS OF

CROSSING-THE INFLUENCE OF DOMESTICATION

ON FERTILITY-CLOSE INTERBREEDING-GOOD AND EVIL RESULTS

FROM CHANGED CONDITIONS OF LIFE-VARIETIES WHEN CROSSED

NOT INVARIABLY FERTILE-ON THE DIFFERENCE IN FERTILITY BE-

TWEEN CROSSED SPECIES AND VARIETIES-CONCLUSIONS WITH RE-

SPECT ΤΟ HYBRIDISM-LIGHT THROWN ON HYBRIDISM BY THE

ILLEGITIMATE PROGENY OF HETEROSTYLED

PLANTS-STERILITY

OF CROSSED SPECIES DUE TO DIFFERENCES CONFINED TO THE

REPRODUCTIVE SYSTEM-NOT ACCUMULATED THROUGH NATURAL

SELECTION-REASONS WHY DOMESTIC VARIETIES ARE NOT MUTUALLY

STERILE-TOO MUCH STRESS HAS BEEN LAID ON THE DIFFERENCE

IN FERTILITY BETWEEN CROSSED SPECIES AND CROSSED VARIETIES

-CONCLUSION
157-175

CHAPTER XX.

SELECTION BY MAN.

SELECTION A DIFFICULT ART-METHODICAL, UNCONSCIOUS, AND NATURAL

SELECTION-RESULTS OF METHODICAL SELECTION-CARE TAKEN IN

SELECTION-SELECTION WITH PLANTS-SELECTION CARRIED ON BY

THE ANCIENTS AND BY SEMI-CIVILISED PEOPLE-UNIMPORTANT

CHARACTERS OFTEN ATTENDED TO-UNCONSCIOUS SELECTION-AS

CIRCUMSTANCES SLOWLY CHANGE, SO HAVE OUR DOMESTICATED

ANIMALS CHANGED THROUGH THE ACTION OF UNCONSCIOUS SELEC-

TION-INFLUENCE OF DIFFERENT BREEDERS ON THE SAME SUB-

VARIETY-PLANTS

AS

AFFECTED

BY UNCONSCIOUS

SELECTION-

EFFECTS OF SELECTION AS SHOWN BY THE GREAT AMOUNT OF

DIFFERENCE IN THE PARTS MOST VALUED BY MAN Pages 176-208

CHAPTER XXI.

SELECTION, continued.

NATURAL SELECTION AS AFFECTING DOMESTIC PRODUCTIONS-CHARAC-

TERS WHICH APPEAR OF TRIFLING VALUE OFTEN OF REAL IM-

PORTANCE-CIRCUMSTANCES FAVOURABLE TO SELECTION BY MAN-

FACILITY IN PREVENTING CROSSES, AND THE NATURE OF THE

CONDITIONS-CLOSE ATTENTION AND PERSEVERANCE INDISPENSABLE

-THE PRODUCTION OF A LARGE NUMBER OF INDIVIDUALS ESPE-

CIALLY FAVOURABLE-WHEN NO SELECTION IS APPLIED, DISTINCT

RACES ARE NOT FORMED-HIGHLY-BRED ANIMALS LIABLE TO DE-

GENERATION-TENDENCY IN MAN TO CARRY THE SELECTION OF

EACH CHARACTER TO AN EXTREME POINT, LEADING TO DIVERGENCE

OF CHARACTER, RARELY ΤΟ CONVERGENCE CHARACTERS CON-

TINUING TO VARY IN THE SAME DIRECTION IN WHICH THEY HAVE

ALREADY VARIED-DIVERGENCE OF CHARACTER WITH THE EX-

TINCTION OF INTERMEDIATE VARIETIES, LEADS TO DISTINCTNESS IN

OUR DOMESTIC RACES-LIMIT TO THE POWER OF SELECTION-LAPSE

OF TIME IMPORTANT-MANNER IN WHICH DOMESTIC RACES HAVE

209-236

ORIGINATED-SUMMARY

CHAPTER XXII.

CAUSES OF VARIABILITY.

VARIABILITY DOES NOT NECESSARILY ACCOMPANY REPRODUCTION-

CAUSES ASSIGNED BY VARIOUS AUTHORS-INDIVIDUAL DIFFERENCES

-VARIABILITY OF EVERY KIND DUE TO CHANGED CONDITIONS OF

LIFE-ON THE NATURE OF SUCH CHANGES-CLIMATE, FOOD, EX-

CESS OF NUTRIMENT-SLIGHT CHANGES SUFFICIENT-EFFECTS OF

GRAFTING ON THE VARIABILITY OF SEEDLING-TREES-DOMESTIC PRO-

DUCTIONS BECOME HABITUATED TO CHANGED CONDITIONS-ON THE

ACCUMULATIVE ACTION OF CHANGED CONDITIONS-CLOSE INTER-

BREEDING AND THE IMAGINATION OF THE MOTHER SUPPOSED TO

CAUSE VARIABILITY--CI:OSSING AS A CAUSE OF THE APPEARANCE

OF NEW CHARACTERS-VARIABILITY FROM THE COMMINGLING OF

CHARACTERS AND FROM REVERSION-ON THE MANNER AND PERIOD

OF ACTION OF THE CAUSES WHICH EITHER DIRECTLY, OR IN-

DIRECTLY THROUGH THE REPRODUCTIVE SYSTEM, INDUCE VARIA-

BILITY

Pages 237-259

CHAPTER XXIII.

DIRECT AND DEFINITE ACTION OF THE EXTERNAL CON-

DITIONS OF LIFE.

SLIGHT MODIFICATIONS IN PLANTS FROM THE DEFINITE ACTION OF

CHANGED CONDITIONS, IN SIZE, COLOUR, CHEMICAL PROPERTIES,

AND IN THE STATE OF THE TISSUES-LOCAL DISEASES-CON-

SPICUOUS MODIFICATIONS FROM CHANGED CLIMATE OR FOOD, ETC.

-FLUMAGE OF BIRDS AFFECTED BY PECULIAR NUTRIMENT, AND

BY THE INOCULATION OF POISON-LAND-SHELLS-MODIFICATIONS OF

ORGANIC BEINGS IN A STATE OF NATURE THROUGH THE DEFINITE

ACTION OF EXTERNAL CONDITIONS COMPARISON OF AMERICAN

AND EUROPEAN TREES-GALLS-EFFECTS OF PARASITIC FUNGI-

CONSIDERATIONS OPPOSED ΤΟ THE BELIEF IN THE POTENT IN-

FLUENCE OF CHANGED EXTERNAL CONDITIONS-PARALLEL SERIES

OF VARIETIES-AMOUNT OF VARIATION DOES NOT CORRESPOND

WITH THE DEGREE OF CHANGE IN THE CONDITIONS-BUD-VARIA-

TION-MONSTROSITIES PRODUCED BY UNNATURAL

TREATMENT-

NISUS FORMATIVUS, OR THE CO-ORDINATING POWER OF THE ORGANISA-

TION ON THE EFFECTS OF THE INCREASED USE AND DISUSE OF

ORGANS CHANGED HABITS OF LIFE- ACCLIMATISATION WITH

ANIMALS AND PLANTS-VARIOUS METHODS BY WHICH THIS CAN

BE EFFECTED-ARRESTS OF DEVELOPMENT-RUDIMENTARY ORGANS.

283-310