TEMPERA TURE-SENSE. 



on different parts of the skin. It includes two dis- 

 tinct things, which are often confounded. In the strict 

 sense of the words, touch is most delicate where the 

 smallest pressure can be felt. In this meaning, the sense 

 of touch is most acute on the forehead and temples, 

 where a lighter weight can be felt than on any other 

 part of the skin. Usually, however, by delicacy of touch 

 is meant the accuracy with which, the eyes being 

 closed, we can tell the exact point of the skin which is 

 touched. In this meaning, the sense of touch is most 

 acute on the tip of the tongue, the edge of the lips, and 

 the ends of the fingers. If the blunted points of a pair 

 of compasses, closed to within one twelfth of an inch, be 

 gently laid, at the same moment, on a finger-tip, we dis- 

 tinguish between them and feel two touches, while on 

 the back of the neck they must be more than an inch 

 apart before we can distinguish them. The papillae of 

 the dermis are always numerous where the distinguish- 

 ing power is great. 



19. The Temperature-Sense. By this is meant our fac- 

 ulty of perceiving cold and heat; and, with the help of 

 these sensations, of perceiving whether things are cold 

 or hot. Its organs are the whole skin, the mucous mem- 

 brane of mouth, pharynx, and gullet, and' of the entry of 

 the nose. Burning the skin will cause pain, but not a 

 true temperature-sensation, which is quite as different 

 from pain as touch is. 



1 8. What is meant by delicacy of touch in the strict sense of the 

 words? Where is it most acute ? What is usually meant by delicacy 

 of touch ? Where is it most acute ? Give an illustration of its variation 

 on different regions of the skin. Where are the papillae numerous? 



jo,. What is the temperature-sense ? What are its organs ? 



