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with them all other sense perceptions have been corrected 

 and compared. 



Dependence of Sight on Muscular Sense and Touch. 



An illustration of the assistance which touch and the mus- 

 cular sense give to the sense of sight is furnished in the 

 case of a boy who had been blind from birth, and received 

 sight at the age of twelve years by means of a surgical 

 operation. At first he could not distinguish a globe from 

 a circular card of the same color until he had touched them. 

 He knew the peculiar features of the dog and the cat by 

 feeling, but not by sight. Happening one day to pick up 

 the cat he recognized for the first time the connection be- 

 tween the new sense of sight and the old familiar ones of 

 touch and the muscular sense. On putting the cat down 

 he said, " So, puss, I shall know you next time." 



Pain. When a heavy weight is laid on the hand it may 

 cause pain. It would at first seem that the ordinary pres- 

 sure sense, when unduly exaggerated, becomes pain. But 

 there seem good reasons for considering pain as a distinct 

 sense from that of touch intensified. It is thought that 

 there are, throughout all parts of the body, nerves of "com- 

 mon sensibility " or " general sensibility," which keep the 

 nerve centers informed as to the condition of all the various 

 tissues, and that ordinarily we have no sensation resulting 

 from the impulses ; to use the language of the psycholo- 

 gist, "they do not rise above the threshold of conscious- 

 ness." They may have some influence in adjusting the 

 action of the different parts. We have seen how the blood- 

 flow to any part is continually adjusted without our know- 

 ing anything about it. But we are usually more or less 

 conscious of the general condition of the body. We call 

 by the name of " common sensations " such feelings as 



