30 EXPERIMENTAL PHYSIOLOGY 



point of stimulation as in previous experiments by raising the end 

 of each lever by the hand when the projecting pin on the drum just 

 touches the vertical needle (see p. 29), making use of the stop. Then 

 take the two tracings of the contraction of the muscle, letting the 

 drum revolve once only, and removing the levers the instant the 

 curves are completed. The difference of latency of the two curves 

 represents the time which it has taken for the wave of contraction 



FIG. 36. Diagram of Aeby's experiment for recording the muscle wave, a, 6, 

 Light straw levers resting on the muscle, which is curarised ; k, k', keys in 

 primary and secondary circuits. 



to pass along the length of the fibres intervening between the two 

 places on which the levers rest. Take a time tracing, and measure 

 this difference, and from it and the length of muscle traversed by the 

 wave (measure with compasses) calculate the rate of propagation of 

 the muscle wave. 



It is essential for the success of this experiment that the muscles 

 used should have most of the fibres running longitudinally and parallel 

 with one another. If very large frogs are obtainable the two sartorius 



