j6 ANIMAL CHEMISTRY LECTURE IV. 



rendered latent in the stretched cross-bow. "When the separated 

 carbo-hydrogen, in the form of some vegetable product, is recom- 

 bined with the evolved oxygen, as in burning coal and wood 

 upon the fire, or in consuming bread and oil and wine in the 

 animal frame, the heat liberated in both instances is nothing 

 more than the heat of the sun which had been stored up in the 

 carbo-hydrate and oxygen respectively. Conversely, the animal 

 frame is a machine in which the sun's energy is set free by the 

 recombination of that oxygen and carbo-hydrate, in the pulling 

 apart of which it had been absorbed or rendered latent. The 

 plant may be regarded as a miser, or hoarder up ; the animal, on 

 the other hand, as a spendthrift, or dissipator, of the sun's force ; but 

 just as the miser is not a producer, or the spendthrift a destroyer 

 of gold, so neither is the vegetable a producer, nor the animal a 

 destroyer of force. All modern philosophy combines to prove 

 that force, like matter, is indestructible. It may be accumulated, 

 but not created ; be dissipated, but not destroyed. The force of 

 every kind, active or latent, existing in the earth, at any given 

 moment, is only the sum of the force received by the earth 



from the sun in excess of the force radiated back from the earth 





 into space. 



(8 1.) Hitherto, in contrasting the functions of animal and 

 vegetable life with one another, I have had regard to their broad 

 general features, looking at each description of life as a whole. 

 A more detailed examination, however, shows us that oxidising 

 and deoxidising processes are common to both kingdoms of 

 nature. For instance, the germination of seeds and maturation of 

 fruits are strictly oxidising, while the conversions of starch and 

 sugar into fat in the animal organism, are strictly deoxidising 

 or vegetative acts. It would seem, indeed, that in all purely 

 nutritive processes, whether of vegetable or animal life, there is an 

 absorption or rendering latent of force, and consequent necessity 

 for its extraneous supply. In highly-developed vegetable life this 

 force is derived directly from the sun. In highly-developed 

 animal life it is obtained by a liberation, within the body, of the 

 sun's force which had been rendered latent in the food we eat 



