o40 Correspondence. [April 



well known and are possessed by birds as well as by most other animals. 

 While the author, in his analysis of the case, has apparently to his own 

 satisfaction eliminated the question of sight and of smell, he seems to have 

 overlooked the application of a third highly developed faculty, that of 

 hearing, to which reference had already been made, in a general way, in 

 his first paragraph. 



One need look no further, it seems to me, than to the remarkably devel- 

 oped functions of sight and hearing in order to arrive at a tenable explana- 

 tion of the first essential and striking phase of the observation made by 

 Mr. Beck, namely, the coming of the vultures so soon and apparently 

 from nowhere, to the scene of action. The hunters, intent upon the 

 chase, had no thought, most likely, for such things as vultures which 

 even at the very time may have been within the range of the men's vision, 

 or, if not, were at no greater distance than was well within the limits 

 of their own superior senses. Whether seen or heard by the birds the 

 action below was beyond doubt sufficient to bring them nearer the scene, 

 for to respond to such and similar stimuli, signals if you please, we may 

 well believe is a function of their inherited instincts. 



And what reason have we to believe that to their well attuned ears the 

 sound of "the voices of the hounds on the twisted night track" was not 

 audible, even from their aerial pathway above the South Mountain? 

 It has been shown, I believe, if my memory serves me aright, from experi- 

 ments in acoustics, that the voice of the dog possesses a remarkable carry- 

 ing quality, perhaps greater than that of any other domestic animal, 

 and that it is the last animal sound that the aviator hears in ascending 

 to a great height. It may safely be assumed, therefore, that to certain 

 birds, especially such as the vultures and other birds of prey, the sound 

 is audible to a very much greater distance than we ourselves are able to 

 appreciate, with our limited powers. 



Having in the first phases of the phenomenon been directed by either 

 the auditory or the visual sense, or for that matter by both, after having 

 reached the ground it may with sound reason be presumed that a little 

 search, their sharp eyes now ably assisted by some degree of olfactory 

 sense, would soon reveal the object of their quest. The time element, 

 which was three hours or more, seems to me entirely adequate, even 

 should the birds have come all the way from their roosting place on the 

 slope of South Mountain. 



As to the analogies drawn by the author from insect life, with respect 

 to a "mating sense," the evidence brought forward seems, in my humble 

 opinion, entirely to lack force even in a "contributive" way, so far as it 

 suggests the existence of a sense different in kind from those which are 

 well known to be present in insects and which have been scientifically 

 proved beyond peradventure. The olfactory sense, if I mistake not, is 

 generally recognized by entomologists as the dominant sense among 

 insects. The degree of refinement it here attains and its "differentiative 



