270 PHYSIOLOGY 



each contraction is a fused series of single contractions, evoked by 

 the discharge along the nerve of between fifty and seventy excita- 

 tions per second. So far therefore the evidence is in favour of the 

 view that voluntary contraction, and, one must add, the tonic con- 

 tractions of all skeletal muscles, are discontinuous in nature and 

 analogous to the tetanus which we may evoke artificially by rapid 

 stimulation either of muscle or of its motor nerve. 



