256 Animal Life and Intelligence. 



the sense of smell. for keeping up some connection with the 

 external world, observed the presence of a stranger in the 

 room, and formed his opinion of people from their charac- 

 teristic smell. On the whole, therefore, we may, perhaps, 

 conclude that the variations in sensitiveness are mainly 

 relative to the needs of life. 



In birds the sense of smell is but little developed, not- 

 withstanding all that most interesting naturalist, Charles 

 Waterton, wrote on the subject. Vultures seem unable to 

 discover the presence of food which is hidden from their 

 sight. Probably reptiles share with them this dulness of 

 the sense of smell. 



It has already been remarked that, in the case of 

 aquatic animals, there is probably little distinction between 

 taste and smell. It would be well, perhaps, to restrict the 

 word " smell " to the stimuli produced by vapours or air- 

 borne particles, and to use the phrase " telsesthetic taste," 

 or simply " taste," for those cases where the effects are 

 produced through the medium of solution. In this case, 

 however, the point to be specially noticed is that taste in 

 aquatic animals becomes a telaBsthetic sense, informing the 

 organism of the presence of more or less distant food. 

 Thus, if you stir with your finger the water in which 

 leeches are living, they will soon flock to the spot, showing 

 that the telsesthetic sense is associated with an appreciation 

 of direction. If a stick be used to stir the water, they do not 

 take any notice of it. Mr. W. Bateson * has shown that 

 there are many fishes, among which are the dog-fish, 

 skate, conger eel, rockling, loach, sole, and sterlet, which 

 habitually seek their food by scent (telsesthetic taste), aided 

 to some extent by touch, and but little, if at all, by sight. 

 " None of these fishes ever starts in quest of food when it is 

 first put into the tank, but waits for an interval, doubtless 

 until the scent has been diffused through the water. 

 Having perceived the scent of food, they swim vaguely 

 about, and appear to seek it by examining the whole area 

 pervaded by the scent, having seemingly no sense of the 



* Journal of Marine Biological Association, New Series, vol. i. Xo. 3, p. 235. 



