104 ELEMENTARY PHYSIOLOGY. XX. 



9. Localisation, (a) A places one hand, say the 

 left, on the table with digits outstretched, the right arm 

 being extended from the side and the eyes shut. At the 

 call of B, A attempts to touch with the forefinger of the 

 right hand the tip of the finger called. B marks on a 

 sketch the result. 



(b) B marks five spots at some distance from another 

 on A's left fore-arm, and makes a sketch of the arm and 

 the spots. B touches one of the spots, and A immedi- 

 ately tries to put his right fore-finger on it. B marks in 

 the sketch the results. 



10. Stimulation of nerve trunk and of nerve- 

 endings. Place the elbow first in warm water, and then 

 in a mixture of ice and water. There will be a sensation 

 of pain in the fingers and cold in the elbow. The appli- 

 cation of cold to the trunk of a nerve does not cause a 

 sensation of cold. 



11. Tactile illusions. Cross the second finger over 

 the first or the third over the second, and place between 

 their tips a small marble (or any solid round body a 

 little larger than a pea) so that it touches the radial side 

 of the first, and the ulnar side of the second finger-tip. 

 On gently rolling the body about, a sensation as if of 

 two distinct bodies will be felt. 



The same illusion is experienced if the tip of the nose 

 be gently rubbed with the tips of the fingers so placed. 



