BIOTIC STRUCTURE AND BIOTIC ENERGY 7 



which is essential to the very existence of the green plant, becomes, 

 at a somewhat higher concentration, a deadly poison to it. 



What is the chemical significance of this great fundamental law 

 of balanced concentrations ? 



Simply this, that the colloids forming the active centres or me- 

 chanisms of living matter, in order to carry out their operations and 

 exchanges, must exist in a delicately balanced mobile equilibrium 

 with the substances upon which they are operating. When such 

 substances become present in too high concentration, the unions 

 with the colloid under the influence of the pressure become too 

 firmly and tightly held ; and conversely if the osmotic pressure, or 

 concentration in solution, is too low, the colloids can no longer keep 

 hold of them in sufficient amount, and they are lost by diffusing out 

 into the surrounding fluids. Between these two limits only lies the 

 working viable range. 



In such a delicately balanced system of crystalloid and colloid in 

 labile union with one another, it is obvious that very slight inter- 

 ference by imported energy from outside will, or may, induce pro- 

 found alterations, and the discharge of energy within the cell under 

 such conditions may be incomparably greater than the inducing 

 energy which may act as a crystal added to a supercooled solution 

 or a spark or detonator applied to an explosive. 



It is in such a way that nerve impulses act, and hormones, 

 enzymes, and cell- excitants generally induce their effects, so as to 

 set in more violent motion a system which is balanced, or at rest, or, 

 contrariwise, to still it from activity into repose. 



Fatigue is a natural example of the retarding influence of the 

 accumulation of the waste products of activity, and this fatigue 

 may either be slowly recovered from or the waste products as they 

 accumulate may give rise to an explosive discharge of activity in 

 which they are removed, and the phase of activity replaces that of 

 momentary fatigue. 



This more momentary fatigue leads to rhythmic activity, while 

 the more permanent fatigue leads to the many times slower rhythm 

 which we ordinarily speak of as fatigue and recuperation. 



The underlying chemical factor differentiating the two forms of 

 rhythmic activity is the structure of the colloidal molecules or 

 aggregates at play in the different forms of tissue, and it is the 

 presence of the more rapid rhythm in cardiac muscle and nerve 

 fibre which renders these tissues infatigable, or indefatigable, in the 



