SMELLS AND MEMORY 185 



unpleasant. Even perfumes carried by some of the in- 

 habitants of Western Europe with the intention of making 

 themselves attractive to their fellow-citizens are often 

 repulsive to a certain proportion of those who come near 

 them, as, for instance, is the case with the extract of the 

 East Indian herb "patchouli." In regard to our other 

 senses there is a general agreement amongst mankind, 

 which extends also to all animals, as to what is agreeable 

 and what is disagreeable. There are definite mathematical 

 laws as to harmony and melody in sound and colour which 

 affect animals and ourselves to a large extent similarly. 

 Sweets are agreeable and bitters are disagreeable, though 

 it is the fact that the snail, which loves sugar, recoils from 

 saccharine, and there are " mites " (Acari) which feed with 

 avidity on bitter strychnine ! Excess of heat and of cold 

 is disliked by animals and all men, whilst the sense of 

 touch is pleasurably or painfully affected in much the same 

 way in most men and animals, more than is the case with 

 regard to any other of the senses. The sense of smell 

 depends upon immediate and personal experience of "asso- 

 ciation " for the determination of pleasure or pain, attrac- 

 tion or repulsion, as the result of its being called into 

 operation. It is a very general experience that odours 

 are more efficient in arousing memory than are mere colour 

 effects or sounds. Not only in animals with acutely 

 developed olfactory powers, but also in man, an odour a 

 peculiar perfume will start a whole chain of reminiscence 

 when sight and sound have failed to do so. It is due to 

 this close association with memory (conscious or uncon- 

 scious) that an odour is agreeable or disagreeable. 



In itself an odour is neither attractive nor repulsive. 

 The acrid fumes of sulphur, chlorine, ammonia, and such 

 bodies are not simply " odours " but corrosive chemical 

 vapours, which act painfully upon the nerves of common 

 sensation within the air-passages of the nose and throat 



