Chap. VII.] THEOKY OF NATURAL SELECTION. 279 



quadruped acquired a long neck and lofty stature, besides 

 the giraffe, and, in a lesser degree, the camel, guanaco, 

 and macrauchenia ? Or, again, why has not any 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 

 belonging to this same order have not acquired either 

 an elongated neck or a proboscis, cannot be distinctly 

 answered ; but it is as unreasonable 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 range 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 interfered with 

 the development of a long neck or proboscis. To reach 

 the foliage at a considerable height (without climbing, for 



