98 STUDIES IN ELECTRO-PHYSIOLOGY: 



the capacity, (2) the greater the capacity the lower the 

 velocity of the current, and (3) the closer the conducting 

 plates are together the greater the capacity. 



In the human body none of the conducting plates, 

 discs, or points are of large area, but while no considerable 

 variation of capacity is possible by this means, Nature can, 

 and apparently does, overcome the difficulty by approach- 

 ing the conductors closely to each other, as in striated 

 muscular fibre, and by connecting them sometimes in 

 parallel (as in Fig. 6). In other parts of the body structure 

 in various arborisations, for instance there must be 

 differences of capacity and resistance, and therefore 

 velocity of current or nerve-impulse cannot be uniform 

 throughout the whole of the nervous system. 



This is an opinion arrived at after experiment and 

 careful thought, and I am encouraged to find myself 

 supported in the view by several authorities. Halliburton 

 says : " The rate of stimulation makes no difference ; 

 however slow or fast the stimuli occur, the nerve-cells of 

 the central nervous system give out impulses at their 

 normal rate. 



" The same is seen in a reflex action. If a tracing is 

 taken from the gastrocnemius of a pithed frog, the muscle 

 being left in connection with the rest of the body, its 

 tendon only being severed and tied to a lever, and if the 

 sciatic nerve of the other leg is cut through, and the end 

 attached to the spinal cord is stimulated, an impulse passes 

 up to the cells of the cord, and is then reflected down to 

 the gastrocnemius under observation. The impulse has 

 thus to traverse nerve-cells ; the rate of stimulation then 

 makes no difference ; the reflex contraction occurs at the 

 same rate, 10 or 12 per second . . . recent experiments by 

 Piper ... he found that each wave of the curve obtained 

 by the graphic method is really itself due to fusion of 

 contractions occurring at a more rapid rate. The method 



