CONTENTS OF VOL. IT. 



Vll 



CHAPTER XXIV. 



LAWS OF VARIATION — USE AND DISUSE, ETC. 



N1SUS FORMATIVUS, OK 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 



0RGANS 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 BE- 

 TWEEN THE SKULL AND EARS — SKULL AND CREST OF FEATHERS — SKULL AND 

 HORNS — CORRELATION OF GROWTH COMPLICATED BY THE ACCUMULATED EFFECTS 

 OF NATURAL SELECTION — COLOUR AS CORRELATED WITH CONSTITUTIONAL 

 PECULIARITIES ojq 



CHAPTER XXVI. 



250 



VDITIO* 3 



LAWS OF VARIATION, continued — SUMMARY. 



ON THE AFFINITY AND COHESION OF HOMOLOGOUS PARTS — ON THE VARIABILITY OF 

 MULTIPLE AND HOMOLOGOUS PARTS — COMPENSATION OF GROWTH — MECHANICAL 

 PRESSURE — RELATIVE POSITION OF FLOWERS WITH RESPECT TO THE AXIS OF THE 

 PLANT, AND OF SEEDS IN THE CAPSULE, AS INDUCING VARIATION — ANALOGOUS OR 

 PARALLEL VARIETIES — SUMMARY OF THE THREE LAST CHAPTERS 339 



atf** 







tfX 



& 





CHAPTER XXVII. 



PROVISIONAL HYPOTHESIS OF PANGENESIS. 



PRELIMINARY REMARKS -FIRST PART :- THE FACTS TO BE CONNECTED UNDER A 

 SINGLE POINT OF VIEW, NAMELY, THE VARIOUS KINDS OF REPRODUCTION — THE 

 DIRECT ACTION OF THE MALE ELEMENT ON THE FEMALE -DEVELOPMENT - 

 THE FUNCTIONAL INDEPENDENCE OF THE ELEMENTS OR UNITS OF THE BODY — 

 VARIABILITY — INHERITANCE — REVERSION. 



SECOND PART : - STATEMENT OF THE HYPOTHESIS - HOW FAR THE NECESSARY ASSUMP- 

 TIONS ARE IMPROBABLE — EXPLANATION BY AID OF THE HYPOTHESIS OF THE 

 SEVERAL CLASSES OF FACTS SPECIFIED IN THE FIRST PART — CONCLUSION . . 357 



