Objects and Methods of Study. 3 



free kidney secretion of cold weather and the prof use perspiration 

 of a hot season are both purely physiological and in the main 

 balance each other. Each under its special environment fulfills 

 an essential work in eliminating from the system toxic materials 

 which would prove hurtful if retained, and thus each is not only 

 physiological but beneficial. If, however, they occurred, not in 

 this mutually compensatory manner, but simultaneously in this 

 profusion, they might well be dreaded as morbid conditions. 

 Again if either were to occur apart from its normal causative en- 

 vironment, if for example the polyuria appeared in hot weather 

 and the perspiration in cold, the phenomenon might fairly be 

 called pathological. In any case if the excessive secretion in- 

 duced a lowering of the general tone of health the process would 

 be essentially a morbid one. In pronouncing therefore upon a 

 morbid process one must take fully into account the correspond- 

 ing physiological process, the attendant conditions, and whether 

 the result is injurious or otherwise. 



The same is true of structural changes. What under given 

 conditions would be essentially a morbid structure, might under 

 other conditions be a simple adaptation to an unwonted environ- 

 ment, and a means of protection from injuries that would other- 

 wise accrue. Excessive growth of cuticular tissue in the epithe- 

 lioma, wart or corn is injurious and essentially pathological, while 

 the callus on the camel's knee or the workman's palm is purely 

 protective and physiological. The local development of a mass 

 of fatty tissue in the average man or beast is a disease, but the 

 tendency to the uniform deposition of fat in the connective tissue 

 of the improved breeds of meat producing animals, is the happy 

 culmination of a long continued and skillful selection and regi- 

 men, without which the live stock industry of today would be a 

 grievous failure. To constitute disease, therefore, modified func- 

 tion must be permanent, and not simply a compensating increase, 

 decrease, or other change, and it must be in some way injurious 

 to the animal economy. Similarly, to constitute disease, modified 

 structure must be other than a simple protective or beneficial 

 change, it must not be a simple evolution in the nature of accom- 

 modation to the environment but it must be a cause of injury to 

 function or a distinct deformity. 



Health may be said to be the harmonious exercise and mutual 



