PROBLEMS OF DISTRIBUTION AND THEIR SOLUTION. 137 



If further evidence were desirable concerning the influence of 

 evolution as explanatory of the distribution of living beings in the 

 past and present of the earth, such opinion might be culled from 

 Sir Charles Lyell. The late eminent geologist remarks, that Buffon, 

 when speculating on "philosophical possibilities," in 1755, ur g e d, 

 " that whilst the same temperature might have been expected, all 

 other circumstances being equal, to produce the same beings in 

 different parts of the globe, both in the animal and vegetable king- 

 doms, yet it is an undoubted fact, that when America was discovered, 

 its indigenous quadrupeds were all dissimilar to those previously 

 known in the Old World." " Thus Buffon," says Lyell, "caught sight 

 at once of a general law in the geographical distribution of organic 

 beings, namely, the limitation of groups of distinct species to regions 

 separated from the rest of the globe by certain natural barriers." In 

 conformity with the doctrine of special centres of creation, as Lyell 

 remarks, the " natural barriers " of Buffon held a perfectly logical 

 place. Separate creations in the New World, and special creations 

 in the Old, separated by intervening oceans, served fully to explain 

 the reasons of the divergence between the animal populations in 

 question. " But," adds Lyell (in further alluding to the close corre- 

 spondence between the fossil forms and the living beings of any 

 given area), "the intimate connection between the geographical 

 distribution of the fossil and recent forms of mammalia, points to 

 the theory (without absolutely demonstrating its truth), that the 

 existing species of animals and plants .... are of derivative origin, 

 and not primordial or independent creations." 



Last of all, Mr. Alfred Russel Wallace to whose labours we owe 

 much, if not the greater part, of the light which has been thrown on the 

 formerly obscure problems of distribution testifies in the most direct 

 terms to the value of the theory of evolution. Towards the firm estab- 

 lishment of this theory he himself has made many important contribu- 

 tions, and has thus aided its place and power in explaining the laws 

 regulating the development of life on the surface of the globe. " We 

 further have to make use of the theory of * descent with modification,' " 

 says Mr. Wallace, " as the only possible key to the interpretation of 

 the facts of distribution ; and this theory," he adds, " has only been 

 generally accepted within the last twenty years. It is evident that so 

 long as the belief in ' special creations ' of each species prevailed, no 

 explanation of the complex facts of distribution could be arrived at, or 

 even conceived ; for, if each species was created where it is now found, 

 no further inquiry can take us beyond that fact, and there is an end of 

 the whole matter." Again, we find a sentence worth quoting, and 

 worth bearing in mind, when Mr. Wallace remarks, that " if we keep 

 in view these facts that the minor features of the earth's surface are 

 everywhere slowly changing; that the forms, and structure, and 



