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EXPERIMENTAL PHYSIOLOGY 



Effect of summation of stimuli. Stimulate the toe (1) with single 

 and -(2) with a succession of interrupted induced shocks. Weak 

 stimuli only need be used. Determine and note down at what distance 

 of the secondary coil from the primary the reflex response is elicited in 

 each case. 



FIG. 85. Turck's method of determining time of reflex to acid-stimulus applied 

 to toes of decapitated frog, a, Beaker of water ; 6, beaker of dilute acid ; 

 c, metronome ; d, hook suspending frog by lower jaw. 



Purposeful reflex action. Place on one flank a piece of paper 

 moistened with acetic acid ; the foot of the same side is raised to 

 rub off the irritant ; if that foot is held down, the other foot may 

 be used. 



After the observation do not leave the acid in contact with the 

 flank, but wash it off by bringing a large beaker of water up over the 

 legs and lower part of the trunk. The experiment may be repeated 

 upon other places ; e.g., the inside of one thigh, the upper part of the 



