468 



THE GEOLOGIST. 



nature, but far more easily, from having incomparably longer time at her dis- 

 posal. Nor do I believe that any great physical change, as of climate or of any 

 unusual degree of isolation to check immigration, is actually necessary to pro- 

 duce new and unoccupied places for natural selection to fill up by modifying 

 and improving some of the varying inhabitants. Tor as all the inhabitants of 

 each country are struggling together with nicely balanced forces, extremely 

 slight modifications in the structure and habits of one inhabitant would often 

 give it an advantage over others ; and stiU further modifications of the same 

 kind would often stiU further increase the advantage. No country can be 

 named in which all the natural inhabitants are now so perfectly adapted to each 

 other, and to the physical conditions under which they live that none of them 

 could any how be improved ; for in all countries the natives have been so far 

 conquered by naturalized productions, that they have allowed foreigners to take 

 firm possession of the land. And as foreigners have thus everywhere beaten 

 some of the natives, we may safely conclude that the natives might have been 

 modified with some advantage, so as to have better resisted such intruders. 

 As man can produce, and certainly has produced, a great result by his methodical 

 and unconscious means of selection, what may not nature effect ? Man can 

 act only on external and visible characters; nature cares nothing for appearances, 

 except in so far as they are useful to any being. She can act on every internal 

 organ — on every shade of constitutional difference — on the whole machinery of 

 life. Man selects only for his own good ; Nature only for that of the being 

 wliich she tends. Every selected character is fully exercised by her: and the 

 being placed under well-suited conditions of life. Man keeps the natives of 

 many climates in the same country ; he seldom exercises each selected character 

 in some peculiar and fitting manner ; he feeds a long- and short -backed pigeon 

 on the same food ; he does not exercise a long-backed, or a long-legged quad- 

 ruped in any peculiar manner ; he exposes sheep with long- and short -wool to 

 the same climate. He does not allow the most vigorous males to struggle for 

 the females. He does not destroy all inferior animals, but protects during each 

 varying season, as far as Kes in his power all his productions. He often begins 

 his selection with some half -monstrous form; or at least by some modification 

 ])romincnt enough to catch his eye, or to be plain and useful to him. Under 

 nature the sliglitest difference of structure, or constitution, may well tm-n the 

 nicely -balanced scale in the struggle for life, and so be preserved. How fleeting 

 are the wishes and efforts of man! how short his time! and, consequently, 

 how poor liis products will be compared with those accumulated by nature 

 during wliole geological periods ! Can we wonder, then, that nature's produc- 

 tions sliouhl be far "truer" in character than man's productions — that they 

 shoidd be intinitcly bettor adapted to the most complex conditions of life, and 

 sliouUl plainly bear the stamp of far higher workmansliip ? It may be meta- 

 phorically said tliat natural selection is daily, hourly scrutinizing throughout the 

 world every variation, even the sli^-htest ; rejecting that which is bad, preserving 

 that Mhich is good; silently and invisibly working whenever and wherever 

 oppoilnnity 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 jirogress 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 only see forms of 

 life are now ditfereut from what they'formcrly were. * * * ^ Slow though 

 the process of selection may be, if f(>eble man can do much by his powers of 

 artilicial selection, I can see no limit to the amount of change, to the beauty 

 niul infinite comiilexity of the co-adaptations between all organic beirgs, one 

 wiih another, and with their physical conditions of life, which may be effected 

 in the long course of time by nature's power of selection." 

 'liie ovidout modifications of primitive type-plans, which indisputedly we see 



