INTRODUCTION 15 



this end the claw of the inner toe is enlarged to form a 

 great spur. But there is no evidence that the skin of 

 the neck is ever damaged in such conflicts as they may- 

 engage in. No scars are ever found, at any rate, to lend 

 support to this theory. The casque, which is similarly 

 supposed to be a mark of honourable conflict, is an " orna- 

 ment " of great frailty, for it is composed of a delicate 

 filigree-work of bone covered with a thin sheath of horn. 

 In like manner, the long plumes which surmount the 

 heads of birds Hke the Peacock, and many Birds of 

 Paradise, and the wattle which surmounts the beak of 

 the Turkey, are supposed to have had their origin in 

 similar pugilistic encounters in the past. Mr. Cunningham 

 is surely pushing the theory of the transmission of 

 acquired characters a little far. For what has been 

 transmitted in these cases is not a number of scarred 

 surfaces, but a series of hypertrophied structures. An 

 amazing array of ornamental characters, symmetrically 

 disposed, and often vividly coloured, in short, has been 

 produced from lacerated tissues which in kind and extent 

 can have varied but little. 



Evidence has been accumulating during the last few 

 years which would have rejoiced the heart of Darwin. Had 

 he known that birds of sober hues " display " with the 

 same animation and with as much elaboration of posture 

 as the Peacock and the Pheasant, his theory of " Sexual 

 Selection " would probably have left little for those 

 who came after him to criticize. Since his time it has 

 been discovered that both permanent and recurrent 

 secondary sexual characters, such as the antlers of deer 

 and the temporary nuptial plumage of birds, such as the 

 Ruff for example, are controlled as to their growth by 

 the stimulating action of the " secretions or juices formed 



