Section IV.-HEALTH AM) DISEASE 



1. INTRODUCTORY 



Health, using the word in a definite sense, is a theoretical condition; 

 it implies perfect correspondence of the organism with the surrounding 

 conditions, and its maintenance includes perfect adaptation of any changes 

 which may occur in either or both. What Mr. Herbert Spencer says of life 

 may be paraphrased so as to apply accurately to conditions of health. 

 Perfect correspondence would be perfect health. Were there no changes in 

 the environment but such as the organism had adapted changes to meet, 

 and were it never to fail in the efficiency with which it met them, there 

 would be unimpaired and perpetual health. That these conditions do not 

 exist in nature is perfectly obvious, and in speaking of health various and 

 modifying terms are used to indicate degrees of health without suggesting 

 the actual existence of disease. If there were an absolute standard of 

 health there would be no difficulty in defining disease; but in reality there 

 is no distinct boundary line, and the transition from health to disease may 

 be so gradual that it might not be possible to say where the one ends and 

 the other begins. 



Disease may be taken in a general sense to mean any disturbance of 

 the structures or functions of a living being. The derangement may be 

 acute when it is severe and rapid in its progress; chronic when it assumes 

 a lower type and is disposed to continue; sporadic when it is the result of 

 ordinary causes arising from without, as exposure to climatic changes, 

 insufficient or impure food; epizootic when it extends to a large number of 

 animals at the same time as the result of some cause which is generally 

 distributed; enzootic when it affects a number of animals in a particular 

 locality owing to local conditions; and recurrent when it exhibits a 

 tendency to return after the affected animals have apparently recovered. 



The science of pathology teaches that the strict meaning of the term 

 disease, or loss of ease, cannot consistently be retained in reference to 

 many morbid conditions because they do not necessarily produce any dis- 

 comfort, and can only be considered as disease for the reason that they are 



