THE ANIMAL AS A MOTOR. 



45 



and the engineer to settle : whether these as yet 

 mysterious processes are not electro-dynamic or related 

 phenomena. 



15. The Processes of the Vital Machines em- 

 ployed in the development of power result mysteri- 

 ously in the production of heat, light, electricity, and 

 dynamic energy by methods still unknown, and with 

 an efficiency of development, transformation, and 

 application frequently, if not always, much greater 

 than has been yet attained by any of the machines 

 devised by man to effect similar results. Mechanical 

 power is exerted at less cost in potential energy sup- 

 plied than in the steam-engine ; heat is evolved as the 

 product of combustion or other action at a low tem- 

 perature, and with insignificant waste by non-utilization 

 in the processes of the animal economy ; light is pro- 

 duced by glow-worms and fire-flies without sensible 

 loss in accompanying thermal or other energy ; and 

 electricity, probably the motor energy of the machine, 

 is produced with similar wonderful economy by pro- 

 cesses of which we have no knowledge. Combustion 

 at ordinary low temperatures, in the tissues of the 

 body; chemical combinations of other kinds in the 

 digestive organs, by the action of peptic substances in 

 solution in the fluids of the system, and other pro- 

 cesses unknown, as yet : these evade the inevitable 

 losses of thermo-dynamic operations in the vital 

 machine, and effect results which are never economi- 

 cally obtainable by the machines of the inventor and 

 mechanic. These constitute a standing riddle and 

 challenge to the man of science and the engineer. 



Lavoisier, as early as 1789, asserted that animals are 

 composed of combustible substances, and that their life 



