314 SCIENCE PROGRESS 



That at least one individual of two species of giant tortoises, 

 which cannot swim in the proper sense of the term, although, 

 as I am informed by my friend Mr, Pocock, they can float, 

 which weigh several hundred pounds each when adult, 

 could have been accidentally carried by currents across six 

 hundred miles of sea, appears beyond the bounds of probability, 

 not to say of possibility. If young individuals were trans- 

 ported on, say, floating timber, it would require two in- 

 dividuals of opposite sexes to be thus carried, before the race 

 could be propagated. 



This, however, is by no means all, for, as the late Dr. Baur 

 observed in the paper cited below, on the accidental transport 

 theory it is impossible to account for the modern Galapagos 

 fauna. " We cannot explain why every, or nearly every island 

 has its peculiar race or species, not represented on any other 

 island. If some animals could be carried over hundreds of 

 miles to the islands, why are they not carried from one island 

 to the other ? But besides that, how could we explain the 

 presence of such peculiar forms as the gigantic land-tortoises, 

 for instance ? According to the elevation theory, we can only 

 think of an accidental importation of these tortoises by some 

 current, because they are unable to swim. After the islands 

 had been elevated out of the sea, it happened once, by a 

 peculiar accident, that a land-tortoise was carried over. Alone 

 it could not propagate. This was only possible after a similar 

 accident imported another specimen of the same species, of the 

 other sex, to the same island. Or we could imagine that at 

 the same time animals of both sexes were thus introduced. 

 By this we could at least explain the population of a single 

 island. But how did all the other islands become populated ? 

 To explain this we should have to invoke a thousand accidents. 



" The most simple solution is given by the theory of sub- 

 sidence. All the islands were formerly connected with each 

 other, forming a single large island; subsidence kept on, and 

 the single island was divided up into several islands. Every 

 island developed, in the course of long periods, its peculiar 

 races, because the conditions on these different islands were not 

 absolutely identical." 



In this passage it cannot fail to be noticed that in the line 

 where he italicised several of the words the author has, no 

 doubt inadvertently, somewhat unjustifiably strengthened his 



