EDITORS INTRODUCTION. 



tendon of the muscle u x would press upon the optic nerve, and thus materially interfere with vision 

 — an inconvenience that by the existing arrangement is totally prevented. Devices like these, whereby 

 special machinery is introduced for special purposes, speak for themselves; we acknowledge their 

 beauty, and in them we recognise at once the wisdom and the goodness of the Creator. 



The sense of smell in birds has afforded subject-matter for much discussion, and great 

 obscurity still exists with reference to the extent to which they make use of their olfactory organs. 

 It has been generally asserted that birds of prey are gifted with an acute perception of odours, and are 

 thus enabled to discover their food at a distance ; but the rapidity with which vultures are known to 

 assemble round the carcase of an animal too recently killed to attract them by putrefactive exha- 

 lations, has induced many ob- 

 servers to consider them as 

 being directed entirely by sight. 

 That this latter is the prefer- 

 able theory appears to be suf- 

 ficiently established by the ex- 

 periments of Audubon, which 

 go to show that these birds 

 possess a sense of smell very 

 far inferior to that conferred 

 upon carnivorous quadrupeds, 

 and that, so far from guiding 

 them to their prey from a dis- 

 tance, it affords them no indi- 

 cation of its presence even 

 when close at hand. 



Having procured the skin of 

 a deer, M. Audubon stuffed it 

 full of hay, and after the whole 

 had become perfectly dry and 

 hard, he placed it in the middle 

 of an open field, laying it down 

 on its back in the attitude of 

 a dead animal. In the course 

 of a few minutes he perceived 

 a vulture flying towards and 

 alighting near it. Quite unsuspicious of the deception, the bird immediately proceeded to attack 

 the carcase, as usual, in the most vulnerable points. Failing in this, he next, widi much exertion, 

 tore open the seams with which the skin had been stitched, and appeared earnestly intent upon 

 getting at the flesh which he expected to find within, and of the absence of which not one of his 

 senses was able to inform him. Finding that his efforts, which were long reiterated, led to no other 

 result than the pulling out of sundry quantities of hay, he at length, though with evident reluctance, 

 gave up the attempt, and took flight in pursuit of other game. 



Another experiment, the converse of the preceding, was then tried : — A large dead hog was 



concealed in a narrow and winding ravine, about twenty feet deeper than the level of the ground 



around it, and filled with briars and high cane. This was done in the montii of July, in a tropical 



climate, where putrefaction takes place with great rapidity ; yet, although many vultures were seen 



2 



Fig. 7. — MUSCLES OF THE EYE-BALL AND OF THE NICTITATING 

 MEMBRANE. 



The Muscles of the Eye-ball, /, q t r, s, arc separated from their origins, and turned aside, to 

 show the " trochlearis " or "quadratus," r, and the " pyramidalis," u, x; the latter of which 

 passes through a loop in the former, so as to gain a double extent of effect with a given length 

 of fibre. 



