A STUDY OF THE SENSES 293 



of the middle finger. Hence, with my eyes closed, I seem 

 to forget that my fingers are crossed, and so draw the wrong 

 conclusion that the two impressions are caused by two dis- 

 tinct objects. 



2. GENERAL SENSES 



Sensations of Temperature. Besides the sensations of touch 

 which we have just described, the skin has the power of. 

 noting differences in the temperature of surrounding objects. 

 If I put my right hand into cold water and my left into hot 

 water, and then plunge both hands into a dish of lukewarm 

 water, the latter will seem warm to my right hand and cold 

 to my left. These temperature sensations may likewise be 

 due to changes in the internal condition of my body. Thus, 

 if I have been exercising vigorously on a windy day and 

 then come into a room the temperature of which is 70, I 

 feel uncomfortably warm. Blood is flowing in large quan- 

 tity through my skin, my temperature terminations send im- 

 pulses to my brain, and I infer that the room is warm. If 

 I act upon impulse, I open a window and sit in a draught. 

 Whereas, if I should keep still until my circulation had 

 returned to its normal condition, I should soon feel comfort- 

 able without taking any risk of catching cold. Since the 

 temperature sense is very delicate in the cheeks and fore- 

 head, where the sense of touch is not well developed, many 

 physiologists conclude that the nervous apparatus is a dif- 

 ferent one for the senses of touch and temperature. 



Sensations of Pain. When I put my finger on a hot stove, 

 I cease to get an impression of temperature, but feel rather 

 a sense of pain. The same is true if an object presses 

 heavily upon any part of the skin. In health we are en- 

 tirely unconscious of the presence of the organs of digestion, 

 circulation, or respiration. But let any one of these in- 

 ternal organs become deranged, and we become conscious of 

 this fact by sensations of pain. Hence we infer that cer- 

 tain nerves are specially adapted to carry to the central 



