UNVERIFIED DEDUCTIONS. l8l 



of the progenitors of electric fishes, and added, 

 " It would be extremely bold to maintain that 

 no serviceable transitions are possible by which 

 these organs might have been gradually devel- 

 oped." Nevertheless, the subject was unap- 

 proachable for him; and his opponents have 

 used the electric fishes as one of the greatest 

 stumbling-blocks in the way of natural selec- 

 tion. Even Romanes felt that the electric 

 fishes present so serious an obstacle that if 

 there were many such he would have to hold in 

 abeyance his belief in the theory. 1 Darwin 

 believed that the facts, because they could not 

 be explained, did not therefore militate against 

 the theory. The much greater difficulty of 

 explaining the case of the electric organs com- 

 pared with that of climbing plants is due to two 

 important facts. In the latter there were at 

 least some gradations of structure and function 

 known ; and even when both were imperfect, it 

 could be shown that they were useful, so that 

 natural selection could act upon them. But 

 there were no imperfectly developed electric 

 organs in fishes which could be appealed to as 

 the source from which the perfect organs might 

 be developed; and what was still more impor- 

 tant, in some of the electric fishes the organs, 



1 Romanes, Darwin and After Darwin. 



