THE SPECIAL SENSES 261 



an operation for the. purpose of forming a new one, by trans- 

 planting a partially removed piece of the skin of the forehead 

 upon the injured part; then, if the new nose be touched or 

 pinched, the feeling is referred to the forehead. This fact 

 illustrates one important truth that the nerves will re-unite 

 after they have been cut and feeling will be restored; if it 

 were otherwise, a succession of slight cuts upon the fingers 

 would seriously impair their tactile sensibility. 



24. The Delicacy of Touch. Although the hand is the 

 proper organ of this sense, yet it is exercised by various parts 

 of the body, their degree of sensibility being proportional to 

 the number of papillae they contain. The varying degrees of 

 tactile delicacy of the different parts of the surface have been 

 measured in an ingenious manner, by means of a pair of com- 

 passes, tipped with small pieces of cork. The two points of 

 the compasses are touched at the same moment to the skin, the 

 eyes being closed, and it is found that, in sensitive parts, the 

 distance between the points may be quite slight, and yet each 

 be plainly felt ; while, in less sensitive parts, the points of the 

 compasses are felt as a single point, although they are sepa- 

 rated one or two inches. 



25. At the tips of the fingers, the distance between the 

 points being one-twentieth qf an inch, a double impression is 

 felt. The distance must be twice as great for the palm, four 

 times as great for the lips, and, on the forehead, it must be 

 twenty times greater. At the middle of the back, where the 

 touch is least acute, the points must be separated more than 

 two inches before they can be separately felt. Therefore, the 

 sense of touch in the fingers is said to be fifty times more 

 delicate than upon the posterior surface of the body. 



26. Exquisite delicacy of touch is attained by practice. 

 This is shown in many of the lighter and more graceful 

 employments of daily life. Without it, the skill of the 

 painter, sculptor, and musician would be rude indeed. By 



24. The delicacy of touch ? Experiments with a pair of compasses ? 



25. Further experiments and results ? 



26. Exquisite delicacy of touch ? The same among the blind ? 



