ii8 THE COURTSHIP OF ANIMALS 



become, so to speak, adopted by selection, than to a 

 response to the oft-repeated stimuli incidental to fighting. 

 The latter explanation is Lamarckian and to-day finds 

 favour with but few. The stimulus theory seems to be 

 effectually discounted by the existence of the spurs on 

 the legs of gallinaceous birds. That these owe their 

 origin to impacts, or blows, seems more than doubtful : 

 and one can hardly see how they could have served any 

 useful purpose until they had attained a sufficient length 

 to serve as weapons. Even if we suppose that the spurs 

 of, say, the Jungle-fowl or the Francolin have been 

 derived from tuberosities such as are found on the legs 

 of the French Partridge {Caccabis fuja)^ we should still 

 lack evidence that the use of the legs in fighting caused 

 the origin of the tuberosities. > 



There is yet another puzzling feature in regard to the 

 armature of the wings, and one which may yet help to a 

 better understanding of the puzzles presented by spurs. 

 A Jacana, one of the Plovers, has the radius broadened 

 or flattened out from its middle onwards to form a flat 

 plate or blade, but the use thereof is unknown. It may 

 possibly serve as a weapon of offence, enabling the bird 

 to beat its rivals with its wings, but from the nature of 

 the structure, and of the effect such a use of the forearm 

 would have upon the hand, it seems doubtful whether 

 it serves any aggressive function. ^ If used at all in 

 fighting it is probably during fights in mid-air, when, 

 after the fashion pursued by the Spur-winged Plover, 

 and even in the case of our own Lapwing, a blow is struck 

 by the uppermost bird at its rival, and often with fatal 

 effect. It is significant to remark, by the way, that in 

 the Lapwing a tubercle answers to the spur of Hoplopterus 

 just as the tubercles of the French Partridge (Caccabis) 



