THE METHOD OF ORGANIC EVOLUTION. 429 



of teu years, we shall have a ijopulatiou two and a half times as great 

 as at first, or, more exactly, if we began with 1,000,000 individuals, then 

 in ten years we should have 2,593,743. This is probably something like 

 what happens. Forty-nine fiftieths of those born never live to breed, 

 yet the population increases steadily so long as conditious are moder- 

 ately favorable, the surplus being got rid of at uncertain intervals by 

 recurrent unfavorable conditions, so as to keep the number of individ- 

 uals on the average about stationary. Looking at it in another way, 

 we find that, beginning with 100 individuals whose offsprings each year 

 amount to 500, of which only 10 survive to breed, then during ten years 

 about 8,000 will have been born, making, with the original iiundred, 

 8,100, out of which only the 100 fittest, or nearly tlie fittest, will 

 survive, to be again weeded out every successive ten years, or there- 

 abouts. Without making some numerical estimate of this kind it is 

 impossible to realize the severity of the struggle continually going on 

 in nature and the resultant elimination of the unfit. With the above 

 figures (which would have to be enormously greater with many species) 

 we see that for every 80 born only 1, on the average, survives to 

 breed. With such an amount of selection it is evident that whenever 

 it hapjiened that the mean point, or "typical center" of the curve of 

 variation, ceased to be the most advantageous point in relation to the 

 whole conditions of existence, then a new typical center would rai)idly 

 be produced by the elimination of all which diverged from it to any 

 injurious extent. There could not possibly be regression from the new 

 typical center unless the inevitable survival of the fittest in a rapidly 

 increasing population can be gotten rid of. 



We are now in a position to discuss Mr. Galton's theory, that there 

 are certain variations which possess "organic stability," and that these 

 are the real factors of evolution " without any help whatever from the 

 process of selection." And first, what is the exact character of these 

 stable variations which form races and ultimately new species by their 

 own inherent force of stability? Is the stability in relation to the 

 actual conditions of the environment or altogether independent of 

 those conditions? If the former, how did it come to be in harmony 

 with them? If this harmonious relation depends upon a mere chance 

 coincidence, we have to consider the comparative rarity of these large 

 or discontinuous variations, and that only a small proportion of them 

 have the alleged character of " stability." Moreover, this class of vari- 

 ations is generally a variation in a single part or organ, and Herbert 

 Spencer (as well as many other writers) has argued forcibly that modi- 

 fications of single characters would in all cases be useless unless 

 accompanied by the correlative modifications of a number of other 

 characters. 1 have myself shown that in the case of individual varia- 

 tions this is no difficulty, because all characters are varying more or 

 less in every generation, and thus the needful harmonious relation 

 between the different organs or i)arts can be easily maintained ; but in 



