416 THE METHOD OF ORGANIC EVOLUTION. 



stiuggle as has been suggested, or that the eliaractei's which vary so 

 much can be of little impoitauce to the species, and can not theiefoie 

 determine survival. But in making tliese objections two consideratious 

 have been overlooked. In the first place, we always compare adults, 

 and an enormous amount of destruction has already taken i)lace during 

 the earlier stages of life. The adults therefore are already a selected 

 group. In the second idace, the struggle is very largely intermittent, 

 owing both to the occurrence only at long intervals of the most adverse 

 meteorological conditions, while the diversity of these conditions leads 

 in each case to the selection of a different characteristic. An excep- 

 tionally severe winter will destroy all which are deficient in one set of 

 characters, while a long drought, or scarcity of some particular kind <jf 

 food, will weed out those deficient in another set of characters. Thus in 

 anj' one year there will exist numbers of individuals which are doomed 

 to speedy destruction under some one of the special adverse conditions 

 which are constantly recurring; and it is this, probably, that explains 

 why there is so much individual variati<m continually i)resent, although 

 the central or typical form remains unchanged for very long periods. 

 This typical form is that which, under existing conditions, survives all 

 the i)eriodical or secular adverse changes, during which the outlying or 

 extreme variations of whatever kind are sooner or later eliminated. It 

 is for want of giving full M'eight to the essentially intermittent nature 

 of the struggle for existence that so many writers fail to grasp its full 

 significance and continually set forth objections and difficulties which 

 have no real importance. 



We are now in a position to estimate the efiiciency of Darwin's theory 

 in explaining the wondrous and complex adaptations that abound in the 

 organic world, as compared with that of Lamarck or of his modern sup- 

 ])orters. And first l^t us take the simple case of the adaptation of 

 fleshy and juicy fruits to be eaten by birds, causing what seems at first 

 sight an injury to the species, but which is really most beneficial, inas- 

 much as it leads to the wide dispersal of the seeds, and greatly aids in 

 the ])erpetuation of the plants Avhich produce such fruits. To what 

 ])ossible direct action of the environment can we impute the production 

 of fleshy or jui(;y pulp, with attractive color and with small, hard-coated 

 seeds, in the innmuerable fruits which are devoured by birds, through 

 whose bodies the seeds i)ass in a state fitted for germination? There 

 is here a combination of characters calculated to a certain end, a defi- 

 nite adaptation. If we suppose that in an early stage of development 

 ancestral fruits which happened to be a little softer than others were 

 eaten by birds, how could that circumstance increase the softness, 

 develop juice, and i)rodu('e color in future generations of the trees or 

 bushes that sprang Irom the Seeds so dispeised ? And if we assume 

 that these several characteristics are positions of "organic stability," 

 acquired through accidental variation, we have to ask why the several 

 kinds of variation occurred together, or Avhy neither of them occurred 



