The Chemical Statics of Organised Beings. 61 



an animal; it becomes, like it, an apparatus of combustion ; it 

 burns carbon and hydrogen ; it gives out heat. 



But, at these same periods, it destroys in abundance the 

 saccharine matters which it had slowly accumulated and stored 

 up. Sugar, or starch turned into sugar, are, then, the primary 

 substances by means of which plants develope heat as required 

 for the accomplishment of some of their functions. 



And if we remark with what instinct animals, and men too, 

 choose for their food just that part of the vegetable in which it 

 has accumulated the sugar and starch which serve it to develope 

 heat, is it not probable, that, in the animal economy, sugar and 

 starch are also destined to act the same part, that is to say, to be 

 burned for the purpose of developing the heat which accompanies 

 the phenomenon of respiration ? 



To sum up, as long as the vegetable preserves its most ha- 

 bitual character, it draws from the sun heat, light, and chemical 

 rays ; from the air it receives carbon ; from water it takes hy- 

 drogen, azote from the oxide of ammonium, and different salts 

 from the earth. With these mineral or elementary substances, 

 it composes the organised substances which accumulate in its 

 tissues. 



They are ternary substances, ligneous matter, starch, gums, 

 and sugars. 



They are quaternary substances, fibrin, albumen, caseum, and 

 gluten. 



So far, then, the vegetable is an unceasing producer ; but if at 

 times, if to satisfy certain wants, the vegetable becomes a con- 

 sumer, it realises exactly the same phenomena which the animal 

 will now set before us. 



V. An animal, in fact, constitutes an apparatus of combustion 

 from which carbonic acid is continually disengaged, in which, 

 consequently, carbon undergoes combustion. 



You know that we were not stopped by the expression cold- 

 blooded animals, which would seem to designate some animals 

 destitute of the property of producing heat. Iron which burns 

 vividly in oxygen produces a heat which no one would deny; but 

 reflection and some science are necessary in order to perceive that 

 iron which rusts slowly in the air disengages quite as- much, 

 although its temperature does not sensibly vary. No one doubts 

 that lighted phosphorus in burning produces a great quantity of 

 heat. Unkindled phosphorus also burns in the air, and yet the 

 heat which it developes in this state was for a long time disputed. 

 So as to animals, those which are called warm-blooded burn 

 much carbon in a given time, and preserve a sensible excess of 

 heat above the surrounding bodies ; those which are termed 

 cold-blooded burn much less carbon, and consequently retain so 



