CONTENTS. 



Introduction Page 1 



CHAPTER I. 



Variation under Domestication. 



Causes of Variability — Effects of Habit — Correlation of Growth — 

 Inheritance — Character of Domestic Varieties — Difficulty of 

 distinguishing between Varieties and Species — Origin of Domestic 

 Varieties from one or more Species — Domestic Pigeons, their 

 Differences and Origin — Principle of Selection anciently followed, 

 its Effects — Methodical and Unconscious Selection — Unknown 

 Origin of our Domestic Productions — Circumstances favourable 

 to Man's power of Selection 7-43 



CHAPTER II. 



Variation under Nature. 



Variability — Individual differences — Doubtful species — Wide 

 ranging, much diffused, and common species vary most — Spe- 

 cies of the larger genera in any country vary more than the species 

 of the smaller genera — Many of the species of the larger genera 

 resemble varieties in being very closely, but unequally, related 

 to each other, and in having restricted ranges . . . . 44-59 



