4 INTRODUCTION. 



consider the geological succession of organic beings throughout 

 time ; in the twelfth and thirteenth, their geographical distribution 

 jhroughout space ; in the fourteenth, their classification or mutual 

 affinities, both when mature and in an embryonic condition. In 

 the last chapter I shall give a brief recapitulation of the whole 

 tvork, and a few concluding remarks. 



No one ought to feel surprise at much lemaining as yet unex 

 plained in regard to the origin of species and varieties, if he make 

 due allowance for our profound ignorance in regard to the mutual 

 relations of the many beings which live around us. Who can 

 explain why one species ranges widely and is very numerous, and 

 why another allied species has a narrow range and is rare ? Yet 

 these relations are of the highest importance, for they determine 

 the present welfare, and, as I believe, the future success and 

 modification of every inhabitant of this world. Still less do we 

 know of the mutual relations of the innumerable inhabitants of 

 the world during the many past geological epochs in its history. 

 Although much remains obscure, and will long remain obscure, I 

 can entertain no doubt, after the most deliberate study and dis- 

 passionate judgment of which I am capable, that the view which 

 most naturalists until recently entertained, and which I formerly 

 entertained namely, that each species has been independently 

 created is erroneous. I am fully convinced that species are not 

 immutable ; but that those belonging to what are called the same 

 genera are lineal descendants of some other and generally extinct 

 species, in the same manner as the acknowledged varieties of any 

 one species are the descendants of that species. Furthermore, I 

 am convinced that Natural Selection has been the most important 

 but not the exclusive, means of modification. 



