LIBERATION OF SOLAR ENERGY BY ANIMALS. JJ 



and air we breathe respectively. But whilst nutritjpn, or the 

 storing up of force, constitutes the chief action of vegetable life, 

 in animal life it occupies an altogether subordinate position. 

 For the prime characteristic of animality is activity, the employ- 

 ment of pent-up force in the production of external acts. 

 Hence, while in the vegetable and animal organism, deoxidising 

 and oxidising processes, constructive and destructive actions 

 alike take place, in the vegetable the destructive are subordinate 

 to the constructive, whilst in animals the constructive are subor- 

 dinate to the destructive acts. * The contraction, for instance, of 

 a man's muscle depends entirely upon the oxidation or destruc- 

 tion of the substance of that muscle, and the equivalent of motion 

 produced upon the amount of muscle destroyed. 



(82.) Thus we perceive that all actions of the animal body are 

 traceable to cosmical force ; that in living as in dead matter there 

 is no creation of force ; and that any explanation of the pheno- 

 nojnena of life which recognises the agency of vital force is 

 simply no explanation at all. Applying the word force as we 

 now do to certain transferable states of actual or potential ac- 

 tivity having quantitative metamorphic correlations, I much 

 question whether the expression chemical force is a correct one, 

 though it is one of which the meaning is perfectly definite and 

 intelligible. By the chemical force of so much oxygen and 

 hydrogen, for instance, we mean the potential energy stored up 

 in them at the moment of their separation, and reproducible 

 from them in the act of their combination. Similarly, we might 

 apply the phrase vital force to the potential energy of so much 

 fat .or muscle, capable by oxidation of being manifested in the 

 form of external heat or motion. But what the physiologist 

 means by vital force I have never been able to understand. So 

 far as I can make out, it seems to be a sort of internal, intrans- 

 ferable, immeasurable, self-originating power, which performs 

 nutritive acts by its absolute will and pleasure ; as if it were not 

 abundantly manifest that the growth of a plant and incubation of 

 an egg cannot be performed without a direct supply, and the 

 development of animal organisms without an indirect supply of 



