o98 THE OUTGO OF ENERGY 



VI 



GENERAL SENSATIONS 

 TlQKLE 



Irradiation. Gently touch the skin near one 

 nostril with a dry camel's-hair brush. 



Note (1) the strong sensation produced by 

 the slight stimulus ; (2) the irradiation beyond 

 the spot stimulated. 



After Image. Repeat the stimulus of the pre- 

 ceding experiment. 



Measure in seconds the time during which 

 the sensation outlasts the stimulus (after image). 



Topography. Test the tickle sensation at vari- 

 ous points on the skin of the face, hands, and 

 forearms. Determine whether the sensation is 

 greatest about the several openings, where skin 

 joins mucous or serous membranes ; e. g., the 

 nostrils, the conjunctival sac, the auditory canal. 

 Do the results indicate a protective mechanism ? 



Summation. In one of the sensitive areas 

 found in the preceding experiment determine the 

 difference between the response to a single stim- 

 ulus and to successive stimuli. 



Fatigue. In any sensitive area determine (1) 

 the quickness with which the apparatus for the 

 sensation of tickle is fatigued ; (2) the duration 

 of fatigue. 



