ALIMENTARY ENERGETICS. 125 



At Other times, again, it is an electrical phenomenon 

 which terminates the vital cycle, and it is, in fact, in 

 this way that things happen in the functional activity 

 of the nerves and muscles in all animals, and in the 

 functional activity of the electrical organ in fish, 

 such as the ray and the torpedo. Finally, the ter- 

 mination may be a photic phenomenon, and this i^ 

 what happens in phosphorescent animals. 



It is idle to diminish the power of these principles 

 by proceeding to enumerate the whole of the ex- 

 ceptions to their validity. We know perfectly well 

 that there are no absolute principles in nature. Let 

 us say, then, that the energy which temporarily 

 animates the living being is furnished to it by the 

 external world under the exclusive form of potential 

 chemical energy; but that, if there is only one door of 

 entry, there are two exits. It may return to the ex- 

 ternal world in the principal form of thermal energy 

 and in the accessory form of mechanical energy. 



§ 2. Measurement of the Supply of 

 Alimentary Energy. 



Calorimetric Method. — From what has preceded it 

 is clear that if the energetic flux which circulates 

 through the animal emerges, iii toto, in the state of 

 heat, the measurement of this heat becomes the 



to do excessive work. The unit of heat, the Calorie, is equivalent 

 to 425 units of work — i.e.^ to 425 kilogrammetres. In the animal 

 at rest, the number of kilogrammetres representing the different 

 quantities of work done is small, the number of corresponding 

 Calories is 425 times smaller. It becomes almost negligeable in 

 comparison with the considerable number of Calories dissipated 

 in the form of heat. 



