4 INTRODUCTION. 



generations, some bird had given birth to a woodpecker, 

 and some plant to the misseltoe, and that these had 

 been produced perfect as we now see them ; but this 

 assumption seems to me to be no explanation, for it 

 leaves the case of the coadaptations of organic beings to 

 each other and to their physical conditions of life, un- 

 touched and unexplained. 



It is, therefore, of the highest importance to gain a 

 clear insight into the means of modification and co- 

 adaptation. At the commencement of my observations 

 it seemed to me probable that a careful study of domes- 

 ticated animals and of cultivated plants would offer the 

 best chance of making out this obscure problem. Nor 

 have I been disappointed ; in this and in all other 

 perplexing cases I have invariably found that our 

 knowledge, imperfect though it be, of variation under 

 domestication, afforded the best and safest clue. I may 

 venture to express my conviction of the high value of 

 such studies, although they have been very commonly 

 neglected by naturalists. 



From these considerations, I shall devote the first 

 chapter of this Abstract to Variation under Domestication. 

 We shall thus see that a large amount of hereditary 

 modification is at least possible ; and, what is equally or 

 more important, we shall see how great is the power of 

 man in accumulating by his Selection successive slight 

 variations. I will then pass on to the variability of 

 species in a state of nature ; but I shall, unfortunately, 

 be compelled to treat this subject far too briefly, as it 

 can be treated properly only by giving long catalogues 

 of facts. We shall, however, be enabled to discuss 

 what circumstances are most favourable to variation. 

 In the next chapter the Struggle for Existence amongst 

 all organic beings throughout the world, which inevi- 

 tably follows from their high geometrical powers of 



