1864.] 225 



tion gain an advantage over their fellows in the Struggle for Existence, 

 and are thus enabled to jostle them on one side and take their places. 

 By a repetition of this process in successive generations the given 

 variation is gradually, by the workings of the Law of Inheritance exag- 

 gerated and swelled into large proportions, until after an indefinitely 

 long ])eriod what we call a new species is formed. — This process Mr. 

 Dai'win calls Natural Selection. 



So far is Mr. Darwin from adopting the old theory, that new species 

 of animals and plants arise merely and entirely or even chiefly from 

 what naturalists call the Conditions of Life, i. e. different food, differ- 

 ent climate, &c., that he expressly on eight distinct occasions repudi- 

 ates that theory. Hear him : — 



Naturalists continually refer to external conditions, such as climate, food, &c., 

 as the only possible cause of variation. In one very limited sense, as we shall 

 hereafter see, this may be true: but it is preposterous to attribute to mere exter- 

 nal conditions the structure, for instance, of the woodpecker, with its feet, tail, 

 beak and tongue so admirably adapted to catch insects under the bark of trees. 

 {Origin of Species, p. 11, Amer. ed.) 



Some little effect may perhaps be attributed to the' direct action of the external 

 conditions of life, and some little to habit; but he would be a bold man wlio 

 would account by such agencies for the differences of a dray and race-horse, a 

 grayhound and bloodhound, a carrier and tumbler pigeon. (Ibid. p. 33.) 



In looking at many small jjoints of difference between species, which, as far 

 as our ignorance permits us to judge, seem to be quite unimportant, we must 

 not forget that climate, food, <&c. probably produce some slight and direct effect. 

 {Ibid. p. SI.) 



How much direct effect difference of climate, food, Ac. produces on any being 

 is extremely doubtful. My impression is, tliat the effect is extremely small in 

 the ease of animals, but perhajjs rather more in that of plants. {Ibid. p. 

 121.) 



We should remember that climate, food, &c. probably have some little direct 

 influence on the organization. {Ibid. p. 175.) 



I fully admit that many structures are of no direct use to their possessors. 

 Physical conditions have probably had some little effect on structure, quite inde- 

 pendently of any good thus gained. [Ibid. p. 178.) 



The dissimilarity of the inhabitants of different regions may be attributed to 

 modification through Natural Selection, and in a quite subordinate degree to the 

 direct influence oi differ enji, physical conditions. {Ibid. p. 305.) 



The complex and little known laws governing variation are the same, as far 

 as we can see, with the laws which have governed the iiroduction of so-called 

 specific forms. In both cases physical conditions seem to have produced but 

 little direct effect. {Ibid. iH).) 



