Criticisms of Theory of Natural Selection. 365 



namely, the case of an adaptive organ the genesis of 

 which could not possibly be attributed to natural selec- 

 tion, and must therefore be attributed to supernatural 

 design. Now, I do not deny that he is here in pos- 

 session of an admirable case a case, indeed, so ad- 

 mirable that it almost seems to have been specially 

 designed for the discomfiture of Darwinians. There- 

 fore, in order to do it full justice, I will show that it is 

 even more formidable than the Duke of Argyll has 

 represented. 



Electric organs are known to occur in several widely 

 different kinds of fish such as the Gymnotus and 

 Torpedo. Wherever these organs do occur, they 

 perform the function of electric batteries in storing 

 and discharging electricity in the form of more or less 

 powerful shocks. Here, then, we have a function 

 which is of obvious use to the fish for purposes both 

 of offence and defence. These organs are everywhere 

 composed of a transformation of muscular, together 

 with an enormous development of nervous tissue ; 

 but inasmuch as they occupy different positions, and 

 are also in other respects dissimilar in the different 

 zoological groups of fishes where they occur, no diffi- 

 culty can be alleged as to these analogous organs 

 being likewise homologous in different divisions of the 

 aquatic vertebrata. 



Now, in the particular case of the skate, the organ 

 is situated in the tail, where it is of a spindle-like 

 form, measuring, in a large fish, about two feet in 

 length by about an inch in diameter at the middle of 

 the spindle. Although its structure is throughout 

 as complex and perfect as that of the electric organ in 

 Gymnotus or Torpedo, its smaller size does not admit 



