138 BIOLOGICAL ASPECTS OF HUMAN PROBLEMS 



examples of disordered function without being able 

 to detect the structural substratum of this change, 

 but this fact should not blind us to the legitimacy of 

 the theoretical conception that every change in 

 function (even within physiological limits) is based 

 on alterations in the structure of the living proto- 

 plasm. Only when these alterations are so profound 

 and so permanent as to entail a lasting decline in 

 function (or an excess of function due to the sup- 

 pression of balancing restraining factors) does the 

 disease take on an irreparable character. 



