454 TROPICAL NATURE 



that each species inhabiting a country was specially adapted 

 to the physical conditions that prevailed there, to which it 

 was exactly fitted. Even if this theory had been true, it was 

 an unproductive ultimate fact, for it was never pretended 

 that we could discover any reason for the limitation of 

 humming-birds and cactuses to America, of hippopotami to 

 Africa, or of kangaroos and gum-trees to Australia ; and we 

 were obliged to believe either that these countries possessed 

 hidden peculiarities of climate or other conditions, or that 

 this was only one out of many unknown and unknowable 

 causes determining the special action of the creative power. 

 All this was felt to be so unsatisfactory that the majority of 

 naturalists openly declared that their sole business was to 

 accumulate facts, and that any attempt to co-ordinate these 

 facts and see what inferences could be drawn from them was 

 altogether premature. In this frame of mind, year after 

 year passed away, adding its quota to the vast mass of 

 undigested facts which were accumulating in every branch of 

 the science. The remotest parts of the globe were ransacked 

 to add to the treasures of our museums, and the number of 

 known species became so enormous that students began to 

 confine themselves not merely to single classes, as birds or 

 insects, but to single orders, as beetles or land-shells, or even 

 to smaller groups, as weevils or butterflies. All, too, were 

 so impressed with the belief in the reality and permanence of 

 species, that endless labour was bestowed on the attempt to 

 distinguish them a task whose hopelessness may be inferred 

 from the fact that, even in the well-known British flora, one 

 authority describes sixty-two species of brambles and roses, 

 another of equal eminence only ten species of the same 

 groups; and it is by no means uncommon for two, five, or 

 even ten species of one author to be classed as a single 

 species by another. All this time geologists had been so 

 assiduously at work in the discovery of organic remains that 

 the extinct species often equalled, and, in some groups 

 as the Mollusca very far exceeded, those now living on the 

 earth, and these were all found to belong to the very same 

 classes and orders as the living forms, and to form part of 

 one great system. Much attention was now paid to the 

 geological succession of the different groups of animals, which 



