426 The Bird 



the motion is more abrupt than is the motion of a pendu- 

 lum. The Mexican motmot is brilHanth' coloured, yet in a 

 densely foliaged tree, among the bright spots of sunlight, 

 it becomes almost invisible. It is the motion of the tail 

 which most often betrays the bird. 



In the tail marked a in Fig. 340 it will be noticed that, 

 where the barbs have not yet been picked off, the unmu- 

 tilated vane is considerably narrowed — an interesting fact 

 for the consideration of evolutionists, as it offers strong 

 circumstantial evidence, but by no means absolute proof, 

 of a case of the inheritance of acquired characters, a much- 

 mooted question not many years ago among scientists. If 

 we choose to accept the evidence thus, we may presume 

 that if this habit is continued through a sufficient number 

 of generations, the vane will, at the point of continued 

 denudation, ultimately ])ecome naturally bare. 



But, in any case, it is a fact which must hold the inter- 

 est of the most superficial bird student that here is a 

 bird which voluntarily tears away a portion of its plu- 

 mage. To the best of our present knowledge this is solely 

 to ornament itself, but the fact that both sexes equally 

 possess this habit makes such an explanation the merest 

 theory. The interest which this has for us here is not the 

 ultimate psychological significance of the habit, but the 

 fact that there is a bird which thus voluntarily mutilates 

 its plumage. As in so many other cases, we must 

 depend on future study of live birds in their natural 

 haunts to clear up the difficulty. It is this very com- 

 plexity of Nature's problems which makes a naturalist's 

 life ever one of enthusiasm and zest. 



