NDITIONS OF LIFE--ON THE NATURE OF SUCH CHANGES--CLIMATE, FOOD,
EXCESS OF NUTRIMENT--SLIGHT CHANGES SUFFICIENT--EFFECTS OF GRAFTING ON THE
VARIABILITY OF SEEDLING-TREES--DOMESTIC PRODUCTIONS BECOME HABITUATED TO
CHANGED CONDITIONS--ON THE ACCUMULATIVE ACTION OF CHANGED CONDITIONS--CLOSE
INTERBREEDING AND THE IMAGINATION OF THE MOTHER SUPPOSED TO CAUSE
VARIABILITY--CROSSING 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 INDIRECTLY THROUGH THE REPRODUCTIVE SYSTEM, INDUCE VARIABILITY
... Page 250

CHAPTER XXIII.

DIRECT AND DEFINITE ACTION OF THE EXTERNAL CONDITIONS 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--CONSPICUOUS MODIFICATIONS FROM CHANGED CLIMATE OR
FOOD, ETC.--PLUMAGE 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 TO THE BELIEF IN THE POTENT
INFLUENCE OF CHANGED EXTERNAL CONDITIONS--PARALLEL SERIES OF
VARIETIES--AMOUNT OF VARIATION DOES NOT CORRESPOND WITH THE DEGREE OF
CHANGE IN THE CONDITIONS--BUD-VARIATION--MONSTROSITIES PRODUCED BY
UNNATURAL TREATMENT--SUMMARY ... Page 271

{vii}

CHAPTER XXIV.

LAWS OF VARIATION--USE AND DISUSE, ETC.

NISUS FORMATIVUS, OR THE CO-ORDINATING POWER OF THE ORGANISATION--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 ... Page
293

CHAPTER XXV.

LAWS OF VARIATION, _continued_--CORRELATED VARIABILITY.

EXPLANATION OF TERM--CORRELATION AS CONNECTED WITH
DEVELOPMENT--MODIFICATIONS CORRELATED WITH THE INCREASED OR DECREASED SIZE
OF PARTS--CORRELATED VARIATION OF HOMOLOGOUS PARTS--FEATHERED FEET IN BIRDS
ASSUMING THE STRUCTURE OF THE WINGS--CORRELATION BETWEEN THE HEAD AND THE
EXTREMITIES--BETWEEN THE SKIN AND DERMAL APPENDAGES--BETWEEN THE ORGANS OF
SIGHT AND HEARING--CORRELATED MODIFICATIONS IN THE ORGANS OF
PLANTS--CORRELATED MONSTROSITIES--CORRELATION BETWEEN THE SKULL AND
EARS--SKULL AND CRES