IS THE BODY A MACHINE? 33 



so much solar energj^ which is stored up by the 

 agency of plant life, and the close comparison 

 between feeding the body to enable it to work 

 and feeding the engine to enable it to develop 

 energy is so evident that it demands no further 

 demonstration. The details of the problem may, 

 however, present some difficulties. 



The first question which presents itself is 

 whether the only power the body possesses is, 

 as in the case with other machines, to transform 

 energy without being able to create or destroy 

 it ? Can every bit of energy shown by the 

 living organism be accounted for by energy 

 furnished in the food, and conversely can all 

 the energy furnished in the food be found 

 manifested in the living organism ? 



The theoretical answer to this question in 

 terms of the law of the conservation of energy 

 is clear enough, but it is by no means so easy to 

 answer it by experimental data. To obtain ex- 

 perimental demonstration it would be necessary 

 to make an accurate determination of the amount 

 of energy an individual receives during a given 

 period, and at the same time a similar measure- 

 ment of the amount of energy liberated in his 

 body either as motion or heat. If the body is a 

 machine, these two should exactly balance, and 

 if they do not balance it would indicate that 

 the living organism either creates or destroys 

 energy, and is therefore not a machine. Such 

 experiments are exceedingly difficult. They 

 must be performed usually upon man rather 

 than other animals, and it is necessary to 

 inclose an individual in an absolutely sealed 

 



