104 ORGANIC EVOLtmON— THE FACTOHS 



account for such examples of extreme evolution as 

 those presented by the special structures of the worker- 

 bee, while the lapsing of inborn variations is sufficient 

 to account for such examples of equally extreme 

 retrogression as those presented by the reproductive 

 organs of that animal, we are entitled to assume that 

 the evolution or the retrogression of the eye is due to 

 the accumulation or to the lapsing of inborn variations 

 alone, unless it can be shown that these causes do not 

 in whole or part sufficiently account for the phenomena, 

 but that these latter must in whole or part be attributed 

 to other causes — i. e. to the effects of use or disuse, to 

 the accumulation or to the lapsing of acquired variations. 



No serious attempt is made by Mr. Spencer to prove 

 that Cessation of Selection is insufficient to account for 

 retrogression in the eyes of cavern-dwelling species ; he 

 sets himself to prove merely that " economy of nutrition " 

 is insufficient, and appears to think that this is all that 

 is necessary. Having destroyed a non-essential out- 

 work he imagines he has conquered the fortress. His 

 error is indicated by Professor Romanes (Contemporary 

 Review, April 1893), but he still maintains his view 

 (pp. 66-7). He is criticizing Professor Weismann's 

 theories, and insists that with that scientist Panmixia 

 — i. e. Cessation of Selection — " is clearly identified with 

 the selection of smaller variations, and for the reason 

 that economy of nutrition is so achieved." I am not 

 concerned in defending Professor Weismann, and if he 

 believes as Mr. Spencer thinks he believes, in my 

 opinion he is wrong. I am bound to say, however, 

 that his works have conveyed an impression to me 

 entirely different. 



When at last Mr. Spencer's attention is forced to 

 Cessation of Selection as a cause of retrogression, he 

 discusses — and dismisses the subject in the following 

 words — 



