THE SENSES 47 



Our senses are popularly numbered as five ; 

 but the appreciation of temperature which the 

 skin possesses should probably be reckoned 

 separately from the sense of touch. In some of 

 the lower animals certain senses are demonstrably 

 stronger than our own : we have no reason to 

 infer that our senses are the only ones that might 

 exist, and it seems likely that insects are endowed 

 with some peculiar detective powers. The males 

 of certain moths (Bombyces) will become aware 

 of a virgin female when at least a mile away, and 

 probably at a much greater distance : insects 

 whose larvae feed upon truffles will detect the pres- 

 ence of these fungi when two feet below the surf ace. 

 Amongst mankind, individuals probably differ 

 very considerably in the delicacy of their senses. 

 Some are colour-blind, others deaf to the charms 

 of music ; and it may be that the "joy of life " 

 which seems specially to exhilarate some indi- 

 viduals and races, proceeds from a keener sensi- 

 bility than is enjoyed by those who take a sober 

 view of life's vicissitudes, or can discover in a 

 fine morning only an opportunity of going out to 

 kill something. But sense organs, however acute 

 and however varied, are, it must be remembered, 

 only receivers : they collect messages from out- 

 side ; but it is in the principal nerve centre the 

 brain that these messages are translated into 

 sensations. We are popularly supposed to hear 

 with our ears, but the ears receive only rhythmical 

 pulsations of air. The brain converts these move- 

 ments into the sensations which we appreciate as 

 sounds, just as the needle and drum of a gramo- 

 phone convert the surface irregularities of the 

 record into a strain of music. It is difficult to real- 

 ise that when we touch an object with the foot the 

 feeling of touch arises not in the foot, but in the 

 brain. But so it is. A man who has lost a leg 



