96 HABIT AND INTELLIGENCE. [cHAP. 



But what is there in the organism to represent this 

 vital energy ? Heat and radiance consist in motion ; 

 magnetism and electricity, probably, in molecular ten- 

 sions ; but in what does vital energy consist ? 

 Its nature This question is at present impossible to answer, and 

 cabk. '" perhaps must ever remain so. But the chemical forms of 

 force are equally inexplicable. We cannot tell in what 

 consists either the static potential energy that becomes 

 actual in combustion or in the voltaic battery, or the actual 

 energy that becomes static in the formation of peroxide 

 of hydrogen, or any other thermo-positive compound. 



I must now proceed to state the proofs of the existence 

 of vital energy in a distinct static form, ^ 



Of course I do not maintain that the whole of the 

 energy due to the oxidation of the food, and of the waste 

 materials of the body, is ever converted into vital energy. 

 Probably by far the greater part of it, in all warm-blooded 

 animals at least, is at once converted into heat, "and used 

 in keeping up the temperature of the body. It is a 

 familiar fact, that whatever increases the activity of respi- 

 ration, also increases the production of animal heat. But 

 there are many phenomena of animal heat which are not 

 capable of being thus accounted for. Though chemical 

 action is the source of the heat as well as of the motor 

 energy produced by the animal organism, no purely 

 chemical theory will account for the local variations of 

 temperature in the body.^ 

 Muscular Muscular action causes an increase of temperature in 

 the acting muscle ; and the increase is greater when the 

 muscle is strained in a "dead pull" against something 

 unyielding, than when it lifts a weight. This is a very in- 

 teresting instance of the law of the equivalence of different 

 forms of energy; the muscular energy which raises a 



1 The only author with whose work I am acquainted, that has distinctly 

 asserted the existence of vital energy in a static form— or, in other words, 

 asserted that the animal organism stores energy — is Dr. Norris, in his 

 Eeport on Muscular Irritability (British Association, 1866, Nottingham). 

 I had, however, thought out the whole theory of static vital energy 

 independently. 



2 Taget, quoted in Carpeuter's Human Physiology, p. 365. 



heat 



