8 ORGANIC DEPENDENCE AND DISEASE 



is a pathological condition involving the normal growth of a 

 living creature, the Bacillus tuberculosis. This condition 

 is a disease only from the point of view of the host of the 

 parasite, that is, of the sufferer. To the parasite it is the 

 normal, though adjusted, mode of life. This, however, is 

 an advanced and complicated example whose history, when 

 worked out, must be determined on the basis of causes pro- 

 ducing such adaptation of parasite to host, and the study 

 of such adaptations must always keep in view the ease with 

 which adaptations have constantly been and are constantly 

 being made. Let us discuss this matter more at length. 



WHAT IS DISEASE? 



We must answer this question in terms of the original 

 use of the word disease is discomfort ; it is thus the early 

 English writers employed it and we must not forget this 

 simple meaning which is not observed in common usages. 

 But in the specific application of the term to physical dis- 

 comfort we shall find Huxley 's definition broad and clear : 

 "Disease . . . is a perturbation of the normal activities 

 of a living body." In this expression by the great Eng- 

 lish physiologist there is a definite implication that disease 

 means disorder of specific function, as we generally under- 

 stand it. But the broader idea in this definition is clear; 

 that disease is any departure from normal living. It may 

 be a departure in a single function or it may involve several 

 functions of physiology; and such an abnormal condition 

 may permeate so many functions as to create a general im- 

 pairment or maladjustment of the entire anatomical ma- 

 chinery. It is elementary, as well as scriptural, to say that 

 seldom can one organic function become impaired without 

 involving others, for no member of the body can say to 

 another, "I have no need of thee." 



There is, however, a still broader conception that we can 

 draw from Huxley's definition and which is of the first im- 



