28 



don't pith it. Leave it for 5 minutes. 3. Hang the frog 

 to the edge of the frogboard, fixing it by a phi through the 

 jaw. Pinch the toes of one foot and observe and record what 

 happens. 



A. Are reflex movements co-ordinated ? Apply a very small 

 scrap of blotting paper dipped hi acetic acid to the flank of 

 the animal. Study and describe the movements. 



Having washed off the acetic acid, study 



B. The relationship of the reflex response to the stimulus ? 

 Pinch the foot with forceps and study the result as regards 



1. Movements which result. (Describe.) 



2. Relation of these movements to the strength of the 



stimulus. Vary the strength of the pinch, or, 

 stimulating with the induced current (Neef's 

 hammer), vary its strength. 



3. Duration of the movements. How long are the- 



movements maintained with different strengths 

 of stimulus ? 



4. Spread of the movements. Study the order of this. 



C. What is the effect of a series of subminimal stimuli in 

 liberating a reflex action ? 



Fit up the apparatus as on p. 26, 2, and stimulate the 

 foot, striking the pins lightly into the skin of the foot, with 



1. Single subminimal stimuli. 



2. A series of subminimal stimuli. 

 CONCLUSION ? 



2. A. Is Time taken up in Reflex Action ? 



METHOD. Using the same frog, dip the foot first into the 

 weak acid supplied, and, after washing in the vessel of water, 

 into the stronger acid. Record the difference in the time 

 of onset of the reflex action. 



3. Is Reflex Action dependent on the Spinal Cord ? 



Now destroy the spinal cord and observe the effect on reflex 

 action. CONCLUSION ? 



