96 



EXPERIMENTAL PHYSIOLOGY 



and there may also be a movement of the upper limbs (spread of 

 excitation). 



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

 and (2) with interrupted induced currents. Determine and note down 



FIG. 78; TURCK'S METHOD OP DETERMINING TURN OP BEPLEX TO ACID-STIMULUS APPLIED TO TOES 

 OP DECAPITATED FROG, a, BEAKER OP WATER ; 6, BEAKER OP DILUTE ACID ; c, METRONOME ; 



d, HOOK SUSPENDING FROG BY LOWER JAW. 



at what distance of the secondary coil from the primary the reflex 

 response is elicited in each case. 



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 pait of the body, and the abdomen, always 

 washing the acid away after each observation. 



