144 THE NATURE AND ORIGIN OF LIFE 



To prove how difficult it is to solve, we have only to point 

 to the differences of opinion among scholars with regard 

 to alcohol. Is alcohol a food ? In other words, is it capable 

 of being transformed within an animal's organism into some 

 other form of energy, chemical as in reserves of living tissues, 

 mechanical as in work ? I believe it difficult to answer 

 the question negatively, but it is quite as difficult to bolster 

 up a positive answer with experiments beyond dispute. We 

 can always ask whether the alcohol itself has been used as 

 a food or whether its presence in the animal economy has not 

 determined a partial consumption of reserves, over which, 

 we can exercise no direct supervision. 



Another difficulty, perhaps even greater, comes from our 

 inability to measure colloid states and to compare them 

 with each other. A variation in the colloid state of a 

 nervous cell, when not accompanied by chemical phenomena, 

 may without any modification in the weight of the individual 

 change its energetic value. And, when accompanied by 

 chemical phenomena, these will consist in exchanges between 

 the cells and the interior medium and such exchanges 

 also are accompanied by no modification in the total 

 weight. 



To use a rough but striking comparison, variations in 

 the colloid state of protoplasm are like the variations in 

 the tension of a string unaccompanied by change of 

 weight. 



An animal that appears inert, that is, executes no apparent 

 anatomical movements, receives from without through 

 its sense organs impressions of light, sound, smell and so 

 on, so that we might think these inflows of energy from 

 without were extinguished in it without producing any 

 modification to verify the principle of equivalents. But 

 the phenomena of centripetal nervous transmission, when 



