214 THE NATUEAL HISTORY 



would often vary and do that by many methods which instinct 

 effects by one alone. Now this maxim must be taken in a 

 qualified sense ; for there are instances in which instinct does 

 vary and conform to the circumstances of place and convenience. 



It has been remarked that every species of bird has a mode of 

 nidification peculiar to itself; so that a school-boy would at once 

 pronounce on the sort of nest before him. This is the case among 

 fields and woods, and wilds ; but, in the villages round London, 

 where mosses and gossamer, and cotton from vegetables, are 

 hardly to be found, the nest of the chaffinch has not that elegant 

 finished appearance, nor is it so beautifully studded with lichens, 

 as in a more rural district : and the wren is obliged to construct 

 it's house with straws and dry grasses, which do not give it 

 that rotundity and compactness so remarkable in the edifices 

 of that little architect. Again, the regular nest of the house- 

 martin is hemispheric ; but where a rafter, or a joist, or a cornice, 

 may happen to stand in the way, the nest is so contrived as to 

 conform to the obstruction, and becomes flat or oval, or compressed. 



In the following instances instinct is perfectly uniform and 

 consistent. There are three creatures, the squirrel, the Jield- 

 mouse, and the bird called the nut-hatch (sitta Europcea), which 

 live much on hazel-nuts ; and yet they open them each in a 

 different way. The first, after rasping off the small end, splits 

 the shell in two with his long fore-teeth, as a man does with his 

 knife ; the second nibbles a hole with his teeth, so regular as if 

 drilled with a wimble, and yet so small that one would wonder 

 how the kernel can be extracted through it ; while the last picks 

 an irregular ragged hole with it's bill : but as this artist has no 

 paws to hold the nut firm while he pierces it, like an adroit 

 workman, he fixes it, as it were in a vice, in some cleft of a tree, 

 or in some crevice ; when, standing over it, he perforates the 

 stubborn shell. We have often placed nuts in the chink of a 

 gate-post where nut-hatches have been known to haunt, and 

 have always found that those birds have readily penetrated 

 them. While at work they make a rapping noise that may be 

 heard at a considerable distance. 



You that understand both the theory and practical part of 

 music may best inform us why harmony or melody should so 

 strangely affect some men, as it were by recollection, for days 

 after a concert is over. What I mean the following passage will 

 most readily explain : 



"Praehabebat porro vocibus humanis, instrumentisque har- 



