SENSE OF TOUCH. 163 



whole swarm is in motion. While a larger proportion of 

 the ants rush out to repel the attack, others, who have the 

 office of guarding the eggs and the larva, or eggs, hasten to 

 remove their charge to places of greater security. These 

 acts all depend on the faculty of touch, so that it is as import- 

 ant to the lower animals as to man. 



19. Sight, hearing, and touch, have been called intellec- 

 tual senses, because they are the means through which we 

 obtain our most valuable information, the witnesses that fur- 

 nish the evidence of the existence of external things. We 

 can have no doubt as to the evidence they deliver, if they all 

 agree in their report. We find however that if we depend 

 on either alone, we are liable to be deceived. (Sight is liable 

 to many illusions^ we may, under the influence of the ima- 

 gination, or of a diseased brain, imagine that^ve see a 

 thousand strange sights, ghosts, hobgoblins, spectres, and 

 devils ; or from similar causes, we may believe that we hear 

 strange and unearthly sounds ; but if we attempt to touch 

 the objects which appear to present themselves to our vision, 

 or which discourse such unnatural music, we find that they 

 vanish before us, like the ignis fatuus, or jack-o'lantern, 

 which we may chase " o'er bog, and o'er moor," but we can 

 never lay our hands upon it. I have often watched, with a 

 degree of wonder, the action of a patient labouring under 

 drunken delirium ; the unhappy maniac not only sees strange 

 objects about his bed, and flitting before his eyes, but he 

 hears them singing and talking to him ; he puts out his hand 

 to grasp them, he grasps nothing, still he is not unde- 

 ceived, nothing can make him believe that what he sees 

 and hears are only the phantoms of a diseased brain ; he per- 

 sists in endeavouring to seize, to touch the strange objects, 

 and only ceases, when after days and nights of incessant 

 vigilance, his strength exhausted, he either sleeps or dies ! 



20. Touch has, therefore, been relied on in every age, as 

 the most certain of our senses,"* and it is well to recollect that 

 the most important fact that ever occurred on the theatre of 



