Chap. vii. Theory of Natural Selection. 1 79 



member of the group acquired a long proboscis ? With respect to 

 S» Africa, which was formerly inhabited by numerous herds of the 

 giraffe, the answer is not difficult, and can best be given by an 

 illustration. In every meadow in England in which trees grow, 

 we see the lower branches trimmed or planed to an exact level by 

 the browsing of the horses or cattle ; and what advantage would it 

 be, for instance, to sheep, if kept there, to acquire slightly longer 

 necks? In every district some one kind of animal will almost 

 certainly be able to browse higher than the others ; and it is almost 

 equally certain that this one kind alone could have its neck 

 elongated for this purpose, through natural selection and the effects 

 of increased use. In S. Africa the competition for browsing on the 

 higher branches of the acacias and other trees must be between 

 giraffe and giraffe, and not with the other ungulate animals. 



Why, in other quarters of the world, various animals belon<nn«- 

 to this same order have not acquired either an elongated neck 

 or a proboscis, cannot be distinctly answered ; but it is as un- 

 reasonable to expect a distinct answer to such a question as 

 why some event in the history of mankind did not occur in one 

 country whilst it did in another. We are ignorant with respect to 

 the conditions which determine the numbers and ran-e of each 

 species ; and we cannot even conjecture what changes of structure 

 would be favourable to its increase in some new country We can 

 however see in a general manner that various causes might have 



To wf Ti h ^ deYel °P ment of a long neck or proboscis. To 

 reach the foliage at a considerable height (without climbing, for 

 which hoofed animals are singularly ill-constructed) implies greatly 

 increased bulk of body and wp bnw +1,0+ e F b y 



qirKrtilorW to 1 i , tIlat S ° me areaS Support 



singularly few large quadrupeds, for instance S. America, though it 

 is so Wiant; whilst S. Africa abounds with them to an u 



Se fo T- 7 Pen °^ S Sh ° Uld W been ™ ch ™re ^om- 



tLfJvZ T enCe than ^ prGSent time ' Wha ^er the 



voTd W I I WG Ca , n SGe that Certain districts and *»« 



3J&w , more , favourable than others for the "p- 



ment oi so large a quadruped as the giraffe 



parts should hi? A a 1 ln <^Pensable that several other 



^hSy^S^'if co ^ a Pted. Although every part of 

 ^^^^^ T f ° ll0W that the pessary parts 

 With the C^ 8 f direction and to the right degree. 



that the parts varVr a diff ^ d ° mesticated anil ^ we know 

 P vary m a dlfferent manner and ^^^ ^ ^ 



k 2 



