THE PHYSIOLOGY OF THE NERVOUS SYSTEM 219 



(5) How many elements enter into the more or less complex 

 perception of equilibrium? Has the tactile or pressure sense of the 

 soles of the feet anything to do with it? Has the muscular sense 

 or sense of muscle tension any part to play? What role does vision 

 play? Are there other factors? Formulate conclusions. 



d. The Muscle Sense. This might better be called the sense of 

 muscle tension. It enters largely into the maintenance of equilibrium. 

 It is an important factor in all voluntary movements because through 

 it one gauges the strength of motor impulse to be used in each 

 movement. 



(6) Take two wooden cylinders of exactly the same shape and size, 

 but differing in weight by an appreciable amount. Let the several 

 members of the group weigh the cylinders in their hands, determin- 

 ing which is the heavier. 



(7) Take two wooden cylinders alike in weight, but differing in size. 

 Let the members of the group test them and describe their sensations. 

 Account for the sensation. 



e. Gustatory Sensation. Prepare the following solutions: 

 (I) 10 grams of cane-sugar in 1 litre distilled water. 



(II) 1 centigram sulphate of quinine in 1 litre distilled water. 



(III) 1 gram glacial acetic acid in 1 litre distilled water. 



(IV) 10 grams dry sodium chloride in 1 litre distilled water. 



(8) To determine the acuteness of taste, take a uniform quantity of 

 the solution into the mouth at each observation. A convenient 

 quantity is 4 c.c. Rinse the mouth with distilled water, or with 

 boiled water, before each test. 



Any person with normal taste is able to detect the taste of the 

 standard solutions. In order to determine how much weaker the 

 solution may be and yet be detected, make dilutions of the standard 

 solutions, recording the final results in number of parts of water to 

 one of the substance in question. 



(9) Tabulate for the class and determine average strength of each 

 solution that marks limit of acuteness. 



(10) Vary the experiments by modifying temperature of solutions 

 (10, 20, 30, and 40 C.). Note latent period. Note whether sub- 

 jects habitually use tobacco. 



(11) Formulate a series of conclusions from the data collected. 



(12) To determine localization of sense of taste i.e., to find 

 whether there are areas of the gustatory region which are especially 

 sensitive to particular stimuli; bitter, for example. 



Through the aid of a probang apply to different limited areas of 

 the tongue, palate, fauces, and buccal mucous surface either the 

 standard solution or somewhat stronger solutions of the same sub- 

 stances. 



Is the tip of the tongue equally sensitive to the four different 

 tastes? The edges? The dorsum? The back? 



