NOTE ON SEXUAL DIMORPHISM, 43 



He criticises my expression " Excessive vitality, " and no doubt I expressed 

 very loosely and in part inaccurately what I meant in an endeavour to be 

 intelligible to a mixed and untechnical audience. 



I intended merely to state Wallace's theory that the catabolic stimulus will 

 act most at the centres of muscular and nervous energy named during the 

 period of salacity. 



Captain Liston has given us very lucidly the physiological explanation of this 

 and here we are in entire agreement. 



But in my remarks I expressly took for granted this theory as the cause 

 " how " these characters came into existence, but stated that it did not answer 

 the question " why," i. e., why these growths, colours, etc., take the form they 

 do in particular cases. 



It is this " why " that Darwin sought to answer by sexual selection. 



Captain Liston cannot explain the " why " except as another example of that 

 beauty in design which we see in all nature. That it is an example of the 

 beauty we find in all God's handiwork I quite agree, but this does not answer 

 our question. 



Captain Liston says he is in entire disagreement with me, when I said that 

 many individual cases would require special explanation and cited the case of 

 the Huia in New Zealand, but he is evidently still thinking of the "how" 

 while I was speaking of the " why." 



With regard to his remarks on colour we are in substantial agreement, and I 

 need occupy your time no further. 



