NUTRITION. 219 



the two categories of phenomena we must try to 

 correlate them. We must try to discover, for 

 instance, what there is in common between the 

 muscle in repose and the muscle in contraction, and 

 to perceive in the muscular tonus a kind of bridge 

 thrown between these two conditions. The functional 

 activity would be uninterrupted, but it would have its 

 degrees of activity. The muscular tonus would be 

 the permanent condition of an activity which is cap- 

 able only of being considerably raised or lowered. 

 Similarly for the glandular functional activity ; the 

 periods of charge must be connected with the periods 

 of discharge. In a word, following the constant path 

 of the human mind in scientific knowledge, after 

 having drawn the distinctions that are necessary to 

 our understanding of things, we must obliterate them. 

 After having dug our ditches we must fill them up 

 again. After having analyzed wc must synthesize. 

 The distinction between the phenomena of functional 

 activity and the phenomena of functional repose or 

 purely vegetative and nutritive activity, though only 

 valid in the case of a provisional and approximate 

 truth, none the less throws light on the obscure 

 regions of biology. 



The succession of energy and repose, of sleep and 

 awakening, is a universal law, or at least a very 

 general law, connected with the laws of energetics. 

 The heart, the lungs, the muscles, the glands, the 

 brain obey in the most obvious manner this obligation 

 of rhythmical activity. The reason is clear. It is 

 because the functional activity involves what is 

 generally a sudden expenditure of energy, and this 

 has to be replaced by what is generally a slow 

 process of reparation. Functional activity is an 



