122 DARWINISM chap. 



that of Darwin or as supplementary to it. Before doing this, 

 however, it will be well briefly to summarise the facts and 

 arguments already set forth, because it is only by a clear 

 comprehension of these that the full importance of the theory 

 can be appreciated and its further applications understood. 



The theory itself is exceedingly simple, and the facts on 

 which it rests — though excessively numerous individually, and 

 coextensive with the entire organic world — yet come under a 

 few simple and easily understood classes. These facts are, — 

 first, the enormous powers of increase in geometrical progres- 

 sion possessed by all organisms, and the inevitable struggle for 

 existence among them ; and, in the second place, the occurrence 

 of much individual variation combined with the hereditary 

 transmission of such variations. From these two great classes 

 of facts, which are universal and indisputable, there necessarily 

 arises, as Darwin termed it, the " preservation of favoured races 

 in the struggle for life," the continuous action of which, under 

 the ever-changing conditions both of the inorganic and organic 

 universe, necessarily leads to the formation or development of 

 new species. 



But, although this general statement is complete and indis- 

 putable, yet to see its applications under all the complex 

 conditions that actually occur in nature, it is necessary always 

 to bear in mind the tremendous power and universality of the 

 agencies at work. We must never for an instant lose sight 

 of the fact of the enormously rapid increase of all organisms, 

 which has been illustrated by actual cases, given in our second 

 chapter, no less than by calculations of the results of un- 

 checked increase for a few years. Then, never forgetting 

 that the animal and plant population of any country is, on 

 the whole, stationary, we must be always trying to realise the 

 ever-recurring destruction of the enormous annual increase, 

 and asking ourselves what determines, in each individual case, 

 the death of the many, the survival of the few. We must 

 think over all the causes of destruction to each organism, — to 

 the seed, the young shoot, the growing plant, the full-grown 

 tree, or shrub, or herb, and again the fruit and seed ; and among 

 animals, to the egg or new-born young, to the youthful, and 

 to the adults. Then, we must always bear in mind that what 

 goes on in the case of the individual or family group we may 



