THE GRASSHOPPER WARBLER. 349 



would throw much light on many of the habits of Vrds, and 

 more especially upon the relation between the economy of 

 nests and the progress of plumification. I would offer a few 

 hints ; but one of our ablest practical physiologists, whose 

 demonstrations, I am proud to say, have in many instances 

 verified conjectures at which I had previously arrived by 

 virtual analysis, has taken up and demonstrated the same 

 view, but has not yet published it ; so that I can only recom- 

 mend the reader to notice the connexion between temperature 

 and the growth of feathers, and also the influence which light 

 has upon eggs. There is a corroborative circumstance in the 

 human body : the hair and nails grow faster 'when the body 

 is heated, as in fever, than when it is cool. 



The obscurity to the sight, and the very peculiar note of 

 the grasshopper bird, give it very considerable interest; and 

 the resemblance which the note has to the sounds emitted 

 by the grasshopper and the mole cricket, often lead to the 

 belief that the bird is in situations which it never visits, and 

 vice versa. 



All the jarring and hissing notes of birds, which probably 

 partake of the nature both of love-calls and of hunting-cries, 

 have something peculiar in them ; they are in so far allied to 

 ventriloquism, that one cannot tell very readily from what 

 precise direction they come. That is one of the reasons why 

 the grasshopper bird is so seldom seen ; it appears to cry in 

 one part of the brake, while it is really in another; and the 

 same thing happens with the crake in the corn-field, the 

 nuthatch on the tree, and several other birds. The direction 

 of the sounding body, whether a bird or anything else, or, 

 indeed, even the fact that there is a sounding body, is not an 

 immediate perception of the organ of hearing, but an act of 

 mind founded on experience ; and that easily explains what 

 is called ventriloquism (an absurd name, by the way), either 

 in man or in birds. Men acquire it by pitching the tone and 



