294 PAIN. 



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 between 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 pressure 

 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 "common sensi- 

 bility" 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 psychologist, "they do not rise 

 above the threshold of consciousness." 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 knowing 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 hunger, thirst, nausea, fatigue, depression, 

 melancholy, restlessness, such as many experience preceding 

 a thunderstorm, the feeling of general discomfort known as 

 malaise, and its opposite, the feeling of general well-being. 

 The body seems to have a set of nerves to give information as 

 to the state of nutrition of the body, and as to its condition 



