NATURAL SELF.CTION 227 



wishes and efforts of man! how short his time! and consequently how 

 poor will be his results, compared with those accumulated by Nature 

 during whole geological periods! Can we wonder, then, that Nature's 

 productions should be far" truer "in character than man's productions; 

 that they should be infinitely better adapted to the most complex 

 conditions of life, and should plainly bear the stamp of far higher 

 workmanship ? 



It may metaphorically be said that natural selection is daily and 

 hourly scrutinizing, throughout the world, the slightest variations; 

 rejecting those that are bad, preserving and adding up all that are 

 good; silently and insensibly working whenever and wherever oppor- 

 tunity offers, at the improvement of each organic being in relation to 

 its organic and inorganic conditions of life. We see nothing of these 

 slow changes in progress, until the hand of time has marked the lapse 

 of ages, and then so imperfect is our view into long-past geological 

 ages, that we see only that the forms of life are now different from what 

 they formerly were. 



In order that any great amount of modification should be effected 

 in a species, a variety when once formed must again, perhaps after a 

 long interval of time, vary or present individual differences of the same 

 favorable nature as before; and these must be again preserved, and 

 so onwards step by step. Seeing that individual differences of the 

 same kind perpetually recur, this can hardly be considered as an 

 unwarrantable assumption. But whether it is true, we can judge only 

 by seeing how far the hypothesis accords with and explains the general 

 phenomena of nature. On the other hand, the ordinary belief that 

 the amount of possible variation is a strictly limited quantity is like- 

 wise a simple assumption. 



Although natural selection can act only through and for the good 

 of each being, yet characters and structures, which we are apt to con- 

 sider as of very trifling importance, may thus be acted on. When we 

 see leaf-eating insects green, and bark-feeders mottled-gray; the 

 alpine ptarmigan white in winter, the red-grouse the color of heather, 

 we must believe that these tints are of service to these birds and 

 insects in preserving them from danger. Grouse, if not destroyed at 

 some period of their lives, would increase in countless numbers; they 

 are known to suffer largely from birds of prey; and hawks are guided 

 by eyesight to their prey — so much so, that on parts of the Continent 

 persons are warned not to keep white pigeons, as being the most liable 

 to destruction. Hence natural selection might be effective in giving 



