350 STUDIES, SCIENTIFIC AND SOCIAL chap. 



struction under some one of the special adverse con- 

 ditions which are constantly recurring ; and it is this, 

 probably, that explains why there is so much individual 

 variation continually present, although the central or 

 typical form remains unchanged for very long periods. 

 This typical form is that which, under existing conditions, 

 survives all the periodical or secular adverse changes, 

 during which the outlying, or extreme variations of what- 

 ever kind, are sooner or later eliminated. It is for want 

 of giving full weight 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. 



Darwinism as compared with Lamarckism. 



We are now in a position to estimate the efficiency 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 supporters. And 

 first let 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, inasmuch as it leads to the wide 

 dispersal of the seeds, and greatly aids in the perpetuation 

 of the plants which produce such fruits. To what possible 

 direct action of the environment can we impute the pro- 

 duction of fleshy or juicy pulp, with attractive colour, and 

 with small, hard-coated seeds, in the innumerable fruits 

 which are devoured by birds, through whose bodies the 

 seeds pass in a state fitted for germination ? There is 

 here a combination of characters calculated to a certain 

 end — a definite adaptation. If we suppose that in an 

 early stage of development ancestral fruits which hap- 

 pened to be a little softer than others were eaten by birds, 

 how could that circumstance increase the softness, develop 

 juice, and produce colour in future generations of the 

 trees or bushes that sprang from the seeds so dispersed ? 

 And if we assume that these several characteristics are 

 positions of " organic stability," acquired through acci- 



