THE DARWINIAN HYPOTHESIS 121 



undiscoverable adaptations to purpose. And we would 

 remind those who, ignorant of the facts, must be moved by 

 authority, that no one has asserted the incompetence of 

 the doctrine of final causes, in its application to physiology 

 and anatomy, more strongly than our own eminent ana- 

 tomist, Professor Owen, who, speaking of such cases, says 

 (On the Nature of Limbs, pp. 39, 40) : " I think it will be 

 obvious that the principle of final adaptations fails to 

 satisfy all the conditions of the problem." 



But, if the doctrine of final causes will not help us to 

 comprehend the anomalies of living structure, the principle 

 of adaptation must surely lead us to understand why 

 certain living beings are found in certain regions of the 

 world and not in others. The palm, as we know, will not 

 grow in our climate, nor the oak in Greenland. The white 

 bear cannot live where the tiger thrives, nor vice versd, and 

 the more the natural habits of animal and vegetable species 

 are examined, the more do they seem, on the whole, limited 

 to particular provinces. But when we look into the facts 

 established by the study of the geographical distribution of 

 animals and plants it seems utterly hopeless to attempt 

 to understand the strange and apparently capricious 

 relations which they exhibit. One would be inclined to 

 suppose d priori that every country must be naturally 

 peopled by those animals that are fittest to live and thrive 

 in it. And yet how, on this hypothesis, are we to account 

 for the absence of cattle in the Pampas of South America 

 when those parts of the New World were discovered ? It 

 is not that they were unfit for cattle, for millions of cattle 

 now run wild there ; and the like holds good of Australia 

 and New Zealand. It is a curious circumstance, in fact, 

 that the animals and plants of the Northern Hemisphere 

 are not only as well adapted to live in the Southern Hemi- 

 sphere as its own autochthones, but are in many cases 

 absolutely better adapted, and so overrun and extirpate the 

 aborigines. Clearly, therefore, the species which naturally 

 inhabit a country are not necessarily the best adapted to 

 its climate and other conditions. The inhabitants of islands 

 are often distinct from any other known species of animal 

 of plants (witness our recent examples from the work of 

 Sir Emerson Tennent, on Ceylon), and yet they have almost 

 always a sort of general family resemblance to the animals 

 and plants of the nearest mainland. On the other hand, 

 there is hardly a species of fish, shell, or crab common to 



