CHASTER : SPECIES AND VARIATION. 25 



three shells found in other parts of the world, twenty-five inhabit 

 the western coast of America, and of these eight are distinguishable 

 as varieties; the remaining eighteen (including one variety) were 

 found by Mr. Cuming in the Low Archipelago, and some of them 

 at the Philippines." 



After an account of the remarkable flora of these islands Darwin 

 summarizes his observations. 



" A vast majority of the land animals and more than half of the 

 flowering plants are aboriginal productions. It was most striking 

 to be surrounded by new birds, new reptiles, new shells, new insects, 

 new plants, and yet by innumerable trifling details of structure, and 

 even by the tones of voice and plumage of the birds, to have the 

 temperate plains of Patagonia, or the hot dry deserts of Northern 

 Chile, vividly brought before my eyes. 



" I have not yet noticed by far the most remarkable feature in the 

 natural history of this archipelago ; it is, that the different islands to 

 a considerable extent are inhabited by diff'erent species. I never 

 dreamed that islands, about fifty or sixty miles apart, and most of 

 them in sight of each other, formed of precisely the same rocks, 

 placed under a quite similar climate, rising to a nearly equal height 

 would have been differently tenanted : but . . this is the case 

 in James Island, of the thirty-eight Galapageian plants, or 

 those found in no other part of the world, thirty are exclusively 

 confined to this island ; and in Albemarle Island, of the twenty- 

 six aboriginal Galapageian plants, twenty-two are confined to this 

 one island . . it is the circumstance that several of these 

 islands possess their own species of the tortoise, mocking-thrush, 

 finches, and numerous plants, these species having the same general 

 habits, occupying analogous situations, and obviously filling the same 

 place in the natural economy of this archipelago, that strikes me with 

 wonder." 



Well might Darwin wonder, for we must not forget that at the time 

 when these observations were made by him, the only explanation of 

 these distinct forms on these geologically recent islands was the 

 supposition that they had been specially created. As we all know 

 the wonder excited by these phenomena bore good fruit. After 

 years of thought, observation, and experiment, he was able to 

 revolutionize all our ideas so that now we confidently assume that 

 these very distinct forms have descended from immigrants and have 

 in course of time acquired new characters which distinguish them 

 from the parental stock of the continent. Now I have quoted 

 portions of this remarkable chapter of the " Naturalist's Voyage 

 round the World " in order to clearly exhibit the problem which 

 confronts us. The problem is — Why do we call these forms distinct 



