INTRODUCTION. 5 



able to variation. In the next chapter the Struggle for 

 Existence amongst all organic beings throughout the 

 world, which inevitably follows from the high geo- 

 metrical ratio of their increase, will be considered. This 

 is the doctrine of Malthus, applied to the whole animal 

 and vegetable kingdoms. As many more indiv i duals 

 o f each species ar e born thanjQan_possibly_survive; .^od^ 

 as^_consequently, therej.s^ a_freg;B£atly---pe&iir-r-ing_&tr]iggle, 

 Iot existenc g,^ it follows that any being, if it vary how - 

 ev^T-slighiLy in an^ man.ner--piafiJ:abl£-.,taJAsLalf,.jind^ 

 t he complex and sometimes varying conditions of life, 

 win have a better c hance of surviving, and , thus be 

 naturally selected. From the strong principle of inheri- 

 tance, any selected variety will tend to propagate its 

 new and modified form. 



This fundamental subject of Natural Selection will 

 be treated at some length in the fourth chapter; and 

 we shall then see how Natural Selection almost in- 

 evitably causes much Extinction of the less improved 

 forms of life, and leads to what I have called Diver- 

 gence of Character. In the next chapter I shall discuss 

 the complex and little known laws of variation. In 

 the five succeeding chapters, the most apparent and 

 gravest difficulties in accepting the theory will be given: 

 namely, first, the difficulties of transitions, or how a 

 simple being or a simple organ can be changed and per- 

 fected into a highly developed being or into an elab- 

 orately constructed organ; secondly, the subject of In- 

 stinct, or the mental powers of animals; thirdly, Hybrid- 

 ism, or the infertility of species and the fertility of 

 varieties when intercrossed; and fourthly, the imperfec- 

 tion of the Geological Record. In the next chapter I 

 shall consider the geological succession of organic beings 



