MOTION IN ANIMALS AND PLANTS. 351 



with that of the excitatory variation, but in the whole organ may 

 last until the development of tension has reached its maximum. 



We huxe further learned that the monophasic \'ariation is a phenom- 

 enon of great regularity, and may be taken as the type from which 

 all other forms of response to stimulation may be derived, either by 

 repetition, prolongation, or interference. 



Although no attempt has been made to settle the question whether 

 the natural contraction of muscle is discontinuous, it has been shown 

 that the electrical phenomena of reflex contraction afl'ord no ground 

 for supposing that it is so. The efficiency of the veratrine spasm 

 seems, at least, to justify us in doubting whether discontinuity is an 

 essential quality of muscular contraction. 



Finally, reasons have been given for thinking that the phenomena 

 known as the ""muscle current" and the "demarcation current" are 

 manifestations of processes which have their seat at the surface of 

 contact between electrode and living muscle. 



