74 



ELECTRO-PHYSIOLOGY 



CHAP. 



most, and provided with two levers, one of which is inserted in 

 the upper half of the muscle just above the intersection, the 

 other in the cartilaginous acetabulum, and if the lower half of 

 the muscle is then excited with single induction shocks, the 

 graphic record of the change in form of both halves of the 

 muscle shows at once that at the moment when the lower and 

 directly excited half begins to shorten, the upper remains pas- 

 sively extended (Fig. 39). 



" But the consequent rise of the upper curve soon changes 

 into a fall below the abscissa, corresponding with a shortening of 

 the upper half of the muscle," which is brought about passive! >/ 



like the previous exten- 

 sion. " As soon as the 

 lower muscle contracts, 

 its two ends are drawn 

 together, i.e. it raises the 

 weight on the one side, 

 and extends the upper 

 half of the muscle on the 

 other. But the weight, 

 once set in motion, rises 

 in virtue of its inertia 

 far beyond the intrinsic 



Fia. 39. o, Upper; u, lower half of muscle. (Mttnzer.) height of lift (' height of 



projection '). At the same 



moment the entire muscle, including the upper half, is unloaded ; 

 the latter flies back, and shortens, thus simulating a natural 

 contraction" (I.e. 251). 



This phenomenon was actually applied by Eegeczy (30) in 

 support of the view that the excitation process passes from one 

 half of the muscle to the other by means of a tendinous inter- 

 section. If all jar is avoided, extension of the upper half of the 

 muscle only will be produced under uniform conditions, persisting 

 so long as the lower half remains contracted. What is here said 

 of a polymerous muscle, divided by a tendinous intersection into 

 two parts, physiologically independent of one. another, applies 

 equally to the two halves of a monomerous, parallel-fibred muscle, 

 e.g. sartorius, the lower end of which is loaded and excited, a 

 light lever being pushed through the centre of the muscle. The 

 upper half of the vertically dependent muscle will always be 



