32 



and note in each case if a series of sensations or a continuous 

 sensation is experienced. The contacts are practically instan- 

 taneous. What CONCLUSIONS do you draw as to the duration 

 of the sensations ? 



//. HOW IS THE TEMPERATURE OF EXTERNAL 

 OBJECTS DETERMINED ? TEMPERATURE 



SENSE. 



I. Is the actual Temperature appreciated ? 



METHODS. Take three basins. 1. Fill one with water so 

 warm that the hand can be just comfortably held in it. 2. 

 Fill another with cold water. 3. Fill the third with water at 

 a temperature intermediate between 1 and 2. 



Place one hand in 1 and the other in 2, and after keeping 

 them there for a few minutes place both in 3 and record the 

 sensation in each hand. What CONCLUSION do you draw as 

 to the precise stimulus of the temperature sense ? 



II. What Factors modify the Sensation ? 



METHOD. Bring a piece of metal and a piece of flannel, 

 which have been kept at the room temperature, upon the skin 

 and notice the difference in the sensation produced. What is 

 the explanation ? 



in. Is the Power of determining Temperature equally distributed 

 over the Skin ? 



METHOD. With a cold metal point gently touch the back 

 of the hand between the fourth and fifth metacarpal bones, 

 and notice if the sensation of cold is produced by contact 

 everywhere or only at certain spots. 



Repeat the experiment with the metal at a higher tempera- 

 ture than the body. 



Repeat the experiment on the back of the forearm. 

 CONCLUSIONS ? 



IV. What is the smallest Difference of Temperature which can 

 be appreciated ? 



METHOD. Take two large test-tubes and place a thermo- 

 meter in each. Half -fill them with water at between 35 and 



