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III. 

 THEORY OF DISEASE. 



Every substance or matter, every chemical or 

 mechanical agency, which changes or disturbs the 

 restoration of the equilibrium between the mani- 

 festations of the causes of waste and supply, in such 

 a way as to add its action to the causes of waste, is 

 called a cause of disease. Disease occurs when the 

 sum of vital force, which tends to neutralize all 

 causes of disturbance (in other words, when the 

 resistance offered by the vital force), is weaker than 

 the acting cause of disturbance. 



Death is that condition in which all resistance on 

 the part of the vital force entirely ceases. So long 

 as this condition is not established, the living tis- 

 sues continue to offer resistance. 



To the observer, the action of a cause of disease 

 exhibits itself in the disturbance of the proportion 

 between waste and supply which is proper to each 

 period of life. In medicine, every abnormal condi- 

 tion of supply or of waste, in all parts or in a single 

 part of the body, is called disease. 



It is evident that one and the same cause of dis- 

 ease will produce in the organism very different 

 effects, according to the period of life ; and that a 

 certain amount of disturbance, which produces dis- 

 ease in the adult state, may be without influence in 



