258 SPECULATIVE SCIENCE 



probable. There is little direct evidence that any of these may- 

 be's actually have been. 



In this essay an attempt has been made to show that many 

 of these assumed possibilities are actually impossibilities, or at 

 the best have not occurred in this world, although it is prover- 

 bially somewhat difficult to prove a negative. 



Let us now consider what direct evidence Darwin brings for- 

 ward to prove that animals really are descended from a common 

 ancestor. As direct evidence we may admit the possession of 

 webbed feet by unplumed birds ; the stripes observed on some 

 kinds of horses and hybrids of horses, resembling not their 

 parents, but other species of the genus ; the generative vari- 

 ability of abnormal organs ; the greater tendency to vary of 

 widely diffused and widely ranging species ; certain peculiarities 

 of distribution. All these focts are consistent with Darwin's 

 theory, and if it could be shown that they could not possibly 

 have occurred except in consequence of natural selection, they 

 would prove the truth of this theory. It would, however, 

 clearly be impossible to prove that in no other way could these 

 phenomena have been produced, and Darwin makes no attempt 

 to prove this. He only says he cannot imagine why unplumed 

 birds should have webbed feet, unless in consequence of their 

 direct descent from web-footed ancestors who lived in the water : 

 that he thinks it would in some way be derogatory to the 

 Creator to let hybrids have stripes on their legs, unless some 

 ancestor of theirs had stripes on his leg. He cannot imagine 

 why abnormal organs and widely diffused genera should vary 

 more than others, unless his views be true ; and he says he 

 cannot account for the peculiarities of distribution in any way 

 but one. It is perhaps hardly necessary to combat these 

 arguments, and to show that our inability to account for certain 

 phenomena, in any way but one, is no proof of the truth of the 

 explanation given, but simply is a confession of our ignorance. 

 When a man says a glowworm must be on fire, and in answer 

 to our doubts challenges us to say how it can give out light 

 unless it be on fire, we do not admit his challenge as any proof 

 of his assertion, and indeed we allow it no weight whatever as 

 against positive proof we have that the glowworm is not on fire. 

 We conceive Darwin's theory to be in exactly the same case ; 



