218 SPECIAL PHYSIOLOGY 



(8) Test blank areas to determine whether their tactile sense is 

 more acute than that of the hot and cold spots. 



(9) Formulate conclusions in answer to the following questions : 

 (a) Are all portions of the skin equally sensitive to temperature 



change ? 



(6) Are all portions of the skin equally sensitive to cold ? 



(c) Are all portions of the skin equally sensitive to heat? 



(d) What percentage of the space in the skin map is sensitive to 

 cold? To heat? 



(10) Place a cold coin on the palm of the hand; the same coin at 

 same temperature on the back of the hand. 



In which of these two positions does the coin feel the larger? 

 Why? 



VII. SENSATION (Continued). 



c. The Sense of Equilibrium. Through the sense of equilibrium 

 one is able to balance the body when sitting, standing, walking, or 

 riding. In order to study some of the phenomena of equilibration 

 try the following experiments: 



(1) Apply a bandage to a subject's head in the horizontal plane. 

 Slip a very sharp pencil (a pen or a needle will answer), point up, 

 behind the bandage in such a way that the point will be held firmly 

 upright by the bandage and register the movements of the head. 



Smoke a kymograph drum; after the drum cools slip the paper off 

 the drum without cutting it. 



Arrange two horizontal arms, adjustable as to width and height, 

 but held parallel by construction of apparatus. Slip the cylinder of 

 carboned paper over the arms and separate them until the paper is 

 stretched and held in two parallel sheets with horizontal surfaces 

 above and below. 



Adjust the carboned surfaces so that when the subject stands 

 erect the point of the pencil (pen or needle) will just touch the lower 

 surface. 



Let the subject take a position beneath the carboned surface, 

 standing erect and as still as possible. Any deviations from the erect 

 position will be traced upon the carboned paper. At the end of 

 one minute close the observation. The paper bears an accurate 

 record of the equilibration of the subject. 



(2) Shift the paper a few inches, exposing a fresh field. Let the 

 subject again take position, standing as still as possible this time 

 with closed eyes. The observation lasts one minute as before. 



(3) Repeat the observation, letting the subject stand upon one foot: 

 (a) with eyes open; (6) with eyes closed. 



(4) Choose another subject as different as possible from the first 

 in stature. Compare his tracings with those of subject number one. 



