146 WHENCE THE FORCE EVOLVED 



we must again go back to anatomy to inquire if the- 

 organs exist to furnish this amount of force. Singu- 

 larly enough, Dr. Beale himself seems to have over- 

 looked this point, for I can find no direct allusion to 

 it. We have first to distinguish between the amount 

 of force required for a stimulus and that required for 

 doing the work. The motor nerve trunk, which sup- 

 plies the muscle as a whole, is certainly sufficient to set 

 agoing the whole apparatus of force extrication within 

 the muscle to its full extent. How much does it con- 

 tribute to the actual work ? The answer is given by 

 an experiment by Matteucci. 



After having carefully determined the minimum 

 duration of the passage of an electric current through 

 a motor nerve needful to cause the contraction of the 

 muscle to which it is distributed, he measured the force 

 expended in exciting the nerve action by calculation 

 from the weight of zinc dissolved in the voltaic battery 

 during the passage of the current. On the other hand, 

 the amount of mechanical work performed showed the 

 force developed in the muscle when contracting under 

 the influence of the nerve action. On comparing these 

 quantities, it was found that the mechanical work per- 

 formed by the muscle during its contraction, was equal 

 to 30,000 times the force expended in producing the 

 nerve excitement (Gavarret, " Phenomenes Physiques," 

 p. 255). 



To discuss the question further, we must consider 

 the processes necessary in the evolution of the force 

 for muscular work ; and for those who may not have 

 the data at hand, I will briefly give the chief facts a& 

 yet known : 



