150 THE DISEASES AND DISOEDERS OE THE OX. 



associates of rest, and we shall hope to show that when some of 

 the associates of work are decisively manifested, there will be a 

 tendency for others \.o appear ; and similarly in the case of the 

 phenomena of rest, these, too, are manifested to a great extent in 

 association with one another. 



The one great aggregate of processes is evoked when the 

 organism must obtain food, eflfect its escape from pursuers, or 

 fight an opponent, when, in short, it must exert itself to the 

 utmost in measures of self-preservation of a direct and active 

 character. The other great division of functions is exemplified 

 when these objects have been met, when the end has been 

 achieved for the tinie being, or when the mechanism of activity 

 concerned in work needs rehabilitation and repair. These two 

 well-marked associations of work and rest, developed in the 

 healthy animal for the ordinary purposes of life, make their 

 appearance also in the field of disease. When thus manifested, 

 certain correlated processes of the one kind or of the other may 

 in some cases work for good. Probably they may more 

 frequently be productive of harm, while in some, unless they be 

 checked, they may actually kill. The organic functions which 

 make up the state of excitement are in reality processes of work, 

 of activity. The efiects of irritation, howsoever produced, those 

 of pain, of joy, of fear, of any impulse to movement of whatever 

 kind, are in some degree similar one to another. In disease we 

 find phenomena corresponding in some measure with those of 

 the chase and the fight, with the defensive measures adopted 

 in cases of fear and so on, and even death may result from 

 excessive and unequilibrated actions of the vital mechanism, as 

 in extreme fear and intense pain. While certain associated pro- 

 cesses may have been, and may still be, of the greatest benefit 

 under certain conditions, they may none the less work great 

 harm, so far as the individual is concerned, under certain other 

 aUied conditions. Thus a reaction, of inestimable value under 

 certain conditions, may be one which under other allied con- 

 ditions can not only serve no useful purpose, so far as we 

 can see, but may even impede or retard recovery to a very 

 considerable extent, and so bring about even a fatal issue. 



Turning now to another but an allied point of view, we remark 

 that the phenomena which constitute day, like those which 

 make up night, have likewise in each case been co -existent for 



