SUMMARY OF PHYSIOLOGICAL DEVELOPMENT. 385 



processes have for their limit a state of equilibrium — proxi- 

 mately a moving equilibrium and ultimately a complete equili- 

 brium. The changes we have contemplated are but the con- 

 comitants of a progressing equilibration. In every aggregate 

 which we call living, as well as in all other aggregates, the 

 instability of the homogeneous is but another name for the 

 absence of balance between the incident forces and the forces 

 which the aggregate opposes to them ; and the passage into 

 heterogeneity is the passage towards a state of balance. And 

 to say that in every aggregate, organic or other, there goes 

 on a multiplication of effects, is but to say that one part which 

 has a fresh force impressed on it, must go on changing and 

 communicating secondary changes, until the whole of the 

 impressed force has been used up in generating equivalent 

 reactive forces. 



The principle that whatever new action an organism is 

 subject to, must either overthrow the moving equilibrium of 

 its functions and cause the sudden equilibration called death, 

 or else must progressively alter the organic rhythms, until, 

 by the establishment of a new reaction balancing the new 

 action, a new moving equilibrium is produced, applies as 

 much to each member of an organism as to the organism in 

 its totality. Any force falling on any part not adapted to 

 bear it, must either cause local destruction of tissue, or must, 

 wuthout destroying the tissue, continue to change it until it 

 can change it no further ; that is — until the modified reaction 

 of the part has become equal to the modified action. What- 

 ever the nature of the force, this must happen. If it is a 

 mechanical force, then the immediate effect is some distortion 

 of the part — a distortion having for its limit that attitude 

 in which the resistance of the structures to further change of 

 position, balances the force tending to produce the further 

 change ; and the ultimate effect, supposing the force to be con- 

 tinuous or recurrent, is such a permanent alteration of form, 

 or alteration of structure, or both, as establishes a permanent 

 balance. If the force is physico-chemical, or chemical, the 



