DIAGNOSIS OF DISEASES. 17 



examination of the patient has been made ; but here, too, care- 

 fully cultivated powers of observation and extensive experience 

 go a good way. To acquire either of these, of course, requires 

 continued carefully and methodically conducted examinations. 

 The same diseases do not always present the same set of symp- 

 toms. Therefore, the more often a disease is seen by the prac- 

 titioner, the more readily will he recognize it. In the course of 

 one and the same disease the symptoms will change, depending 

 upon whether the onset, acme or latter stages are being ob- 

 served. The diagnostician should be like the experienced 

 botanist who recognizes a plant in all its stages of vegetation. 

 There will always remain a few cases the symptoms of which 

 are so atypical that an exact diagnosis is impossible. 



Not infrequently, however, even the experienced prac- 

 titioner must content himself with limiting his diagnosis to a 

 statement of the general character of the disease and reserve 

 the privilege of expressing his final opinion {special diagnosis) 

 pending further observation and developments. This is par- 

 ticularly the case in the first outbreaks of infectious diseases 

 when localized changes are absent and in many chronic dis- 

 eases showing few symptoms. 



We also distinguish between a definite, a probable, and 

 a possible diagnosis. 



