THE CENTRAL NERVOUS SYSTEM 381 



APPARENT PURPOSE IN EEFLEX ACTION 



1. Destroy the brain of a frog with the seeker. 

 Dip small pieces of filter paper in strong acetic 

 acid. Kemove the superfluous acid, lay the 

 paper bearing the acid on (1) the frog's thigh, 

 (2) the foot, (3) the back. After each stimulation 

 note the character of the reflex movement, and 

 then carefully wash the acid from the skin. 



The movements are related to the areas stimu- 

 lated in a certain purposeful way. Efforts are 

 made apparently to brush away the acid paper. 



2. Place the acid on the flank of the right leg. 

 Usually the leg stimulated strives to brush away 

 the paper. Hold this leg fast. 



The other leg (the left) will be used to re- 

 move the acid from the opposite limb. (This 

 experiment succeeds best in strong, lively frogs.) 



3. Place an uninjured frog in an evaporating 

 basin containing sufficient water to immerse the 

 frog to the neck and covered with wire gauze 

 to keep him from jumping out. Warm the 

 water. 



As the temperature rises to from 20-30 C. 

 the frog will attempt to escape. 



Eepeat the experiment with the frog the brain 

 of which has been destroyed. 



No movements of escape will be noticed. 



