THE SPECIAL SENSES 273 



22. The sense of touch assists the other senses, especially 

 that of sight, giving foundation and reality to their perceptions. 

 Without it, the impressions received by the eye would be as 

 vague and unreal as the figures that float through our dreams. 

 A boy who had been blind from birth, at the age of twelve 

 years received sight by means of a surgical operation ; at first, 

 he was unable to distinguish between a globe and a circular 

 card of the same color before he had touched them. After 

 that, he at once recognized the difference in their form. He 

 knew the peculiarities of a dog and a cat by feeling, but not 

 by sight, until one day, happening to take up the cat, he recog- 

 nized the connection of the two sorts of impressions --these of 

 touch and sight; and then, putting the cat down, U3 sai^ : 

 " So, Puss, I shall know you next time." 



23. Of all the senses, touch is considered the least liable to 

 error; yet, if that part of the skin by which the sense is 

 exercised is removed from its customary position, a false 

 impression may be created in the mind. This is well illus- 

 trated by an experiment, which dates from the time of Aris- 



Fio. 61 



totle. If we cross the middle finger behind the forefinger, 

 and then roll a marble or some small object upon the tips of 

 the fingers (see Fig. 61), the impression will be that two- mar- 

 bles are felt. If the fingers, thus transposed, be applied to 

 the end of the tongue, two tongues will be felt. When the 

 nose is accidentally destroyed, the surgeon sometimes performs 



22. Importance of the sense of touch to the development of the other senses ? 



23. Liability of touch to err ? Describe the illustration. 



