CH&<PTE<R IV. 



Special pathology 



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Therapeutics. 



Introduction. 



Before entering upon the consideration of individual diseases, it may 

 be well to understand certain points of distinction, interesting and of prac- 

 tical importance. 



Differences as regards severity and duration, constitute a basis of the 

 division of diseases into varieties. The same disease may be either acute, 

 subacute, or chronic. A disease is acute when it has a certain degree of in- 

 tensity, and runs a rapid course. The subacute variety has less intensity ; 

 a disease of moderate activity. The chronic variety exists when a disease 

 is subacute, and it is of long continuance. The division into varieties based 

 on the difference just named, is especially applicable to inflammatory 

 affections. 



A point of distinction of practical importance relates to duration. Some 

 diseases continue for a definite period, never exceeding certain limits in 

 this regard. Those which tend intrinsically to end after a certain time, 

 are distinguished as self limited. 



In the list of individual diseases, are some recognized as such for the 

 sake of convenience, but which in reality, are only effects or symptoms of 

 disease, as for example, jaundice and dropsy, which are merely symptoms 

 occurring in connection with different affections. 



It will be observed that the term expectant is often used, the treatment 

 of a disease by expectation, consists in watching carefully its progress, 



