54 HABITS AND INSTINCTS OP ANIMALS. CHAP. II. 



fact, is as circular as that of their natural affinities. If, 

 however, we were to single out any one particular sense, 

 and then expect, as a matter of course, to find it most 

 conspicuous among quadrupeds, we shall, probably, be 

 disappointed. It is not by such a criterion that we 

 are to judge of the perfection just mentioned, as be- 

 longing to quadrupeds ; but rather from these animals 

 being gifted with a greater proportion of all the five, 

 than falls to the lot of any other division of the ver- 

 tebrated circle. Take, for instance, the faculty of sight, 

 and there can be no question that it has been given to 

 birds in a much higher degree than quadrupeds ; and 

 this, for special reasons ; the objects which the great 

 majority feed upon are small ; they are often to be dis- 

 tinguished while the bird is traversing the air, and 

 they are to be searched for with great assiduity. This 

 last condition, indeed, is imposed upon quadrupeds ; 

 but then these latter are aided, in a great measure, by 

 a high power of smelling, which birds obviously do 

 not possess. " A hawk," observes Buffon, " during its 

 aerial soaring, will discern a lark upon a clod of earth, 

 coloured almost exactly like itself, at twenty times the 

 distance at which a man or a dog can perceive it. A 

 kite, having soared to an elevation beyond our ordinary 

 vision, can distinguish lizards, field mice, and small 

 birds, and select those upon which he chooses to pounce." 

 This great extent of sight is accompanied with a cor- 

 responding degree of precision ; for the organ being at 

 once both extremely elastic and extremely sensitive, the 

 eye becomes round or flat, is covered or uncovered, con- 

 tracts or diktes, and speedily and alternately assumes 

 all the forms necessary to adapt itself to every degree 

 of light or distance. " Moreover," continues the same 

 author, " as the sense of sight is the only one which pro- 

 duces the ideas of motion the only one by which the 

 degrees of space which are traversed can be compared, 

 and birds being, of all animals, the best adapted for 

 motion, it is not surprising that they possess, in the 

 highest degree of certainty and perfection, that sense 



