ANIMAL MECHANISM. 59 



that new analogies will still show themselves between these 

 two manifestations of force in living beings, mechanical work 

 and electricity. 



CHAPTER VII. 



ANIMAL MECHANISM. 



Of the forms under -which mechanical work presents itself Every 

 machine must be constructed with a view to the kind of work which 

 it has to perform Correspondence of the form of muscle with the work 

 which it accomplishes Theory of Borelli Specific force of muscles 

 Of machines ; they only change the form of work, but do not 

 increase its quality Necessity of alternate movements iu living 

 motive powers Dynamical energy of animated motors. 



If we have lingered long over the origin of heat, of 

 mechanical work, and of electricity in the animal kingdom, 

 it was in order to establish clearly that these forces are the 

 same as those which are seen in the inorganic world. Certain 

 evident differences must have struck the earlier observers, but 

 the progress of science has shown, more and more clearly, 

 this identity, which is now disbelieved only by those whose 

 minds are still under the influence of obsolete theories. 



Mechanical force, to which our attention must now be 

 exclusively directed, has hitherto been studied only in its 

 origin ; we must follow it through all its applications to 

 work of different kinds which it executes in animal me- 

 chanism. 



In all the machines employed in the arts we must have 

 organs which serve as media between the forces which we 

 employ and the resistance which are required to be overcome. 

 This word organ is precisely that which anatomists use to 

 designate the portions which compose the animal machine. 

 The laws of mechanics are applicable as well to animated 

 motors as to other machines ; this truth, however, has to be 

 demonstrated, but, like many ethers, it was for a long time 

 unrecognized. 



