SENSE OF SMELL. 187 



object at a great distance, but that they can smell food a 

 quarter of a mile off we have no proof whatever ; and as we 

 can account for the phenomenon by their sight, it is unne- 

 cessary to have recourse to their other faculties.'* Every 

 person who has seen the manner in which crows collect 

 together about a dead animal in the country, will be satis- 

 fied that the above is a correct explanation of the pheno- 

 menon. 



20. The olfactory organs of reptiles are but slightly 

 developed. Frogs have two small holes, which serve as the 

 organs of smell. The pituitary membrane of the turtle is 

 of a very dark colour, and the nerve is of considerable size. 

 In serpents, they are more elongated, and in lizards still 

 more so. The animals of this class have no cavities corres- 

 ponding to the sinuses ; of course the sense of smell cannot 

 be very acute. 



21. The smell can be greatly improved by education. 

 Humboldt states, that the Peruvian Indians can distinguish 

 in the middle of the night the different races by their smell ; 

 whether they are European, negro, or American Indian. 

 By habit, the perfumer acquires the faculty of distinguishing 

 the nicest shades of odours. We see the influence of educa- 

 tion, by the difference between a dog that has been trained 

 to the chase, and one that has not. In the blind, the sense 

 of smell is particularly acute. A boy in Edinburgh, who was 

 born blind and deaf, could tell the entrance of a stranger in- 

 to the room by the smell alone ; and he told one person from 

 another by smelling at him. 



22. Dr. Good remarks, that " we occasionally meet among 

 mankind with a sort of sensation altogether wonderful and 

 inexplicable. There are some persons so peculiarly affected 

 by the presence of a particular object, that is neither seen, 

 tasted, smelt, heard, or touched, as not only to be conscious 

 of its presence, but to be in agony till it is removed. The 

 vicinity of a cat not unfrequently produces such an effect ; 

 and I have been a witness to the most decisive proofs of this 



