APPENDIX I. Ill 



then again gradually relaxes. The results obtained 

 by M. Pouillet's method regarding the successive 

 stages of contraction are thus confirmed by the 

 graphic method. The curve traced by the contract- 

 ing muscle of course becomes the more stretched 

 the quicker the cylinder rotates, but, at an equal 

 rate of rotation, the curves traced successively by 

 the same muscle, stimulated by a current capable of 

 giving rise to the maximum of contraction, coincide 

 so as almost entirely to coalesce, so long as the 

 muscle does not become exhausted. This also hap- 

 pens when in repeated trials the current, instead of 

 on the muscle itself, is made to act with sufficient 

 energy upon always the same part of the nerve, say 

 the part A ; only all the curves thus obtained are 

 found to start a little further from s on the datum- 

 line, say at a. 



But, on stimulating the nerve alternately at a 

 place A nearer to, and B farther from, the muscle, 

 the curves obtained no longer coincide. They 

 separate, and the curves traced on stimulating B 

 will again be found to lie farther off on the datum- 

 line, starting at b instead of at a, and keeping every- 

 where the same horizontal distance a b from the 

 curve traced when A is stimulated. 



This horizontal distance of the two curves, or sets 

 of curves, evidently corresponds to the time the 

 nervous agent has spent in travelling along the 

 nerve from B to A. It is, in* fact, the displacement 

 of the surface of the cylinder which, according to 

 its angular velocity, has occurred during the same 

 time. Determining this angular velocity by means 



