CAUSES OF DISEASE. 17 



to make it impossible for the patient to say when he 

 really began to feel ill. This slow insidious manner 

 of onset is the rule in typhoid fever and pulmonary 

 tuberculosis. 



After the period of invasion comes the 

 Stationary stationary period, the symptoms of which 

 Period. are so characteristic for each particular 



infectious disease as to form the basis for 

 our classification of infectious diseases in general, and 

 of identification of any one in particular. If the 

 invasion be sudden, the stationary period is usually 

 quickly reached (in pneumonia, a few hours) ; if gradual, 

 the stationary period may be prolonged a week or more 

 (e.g., typhoid fever). The stationary period presents 

 more or less uniformity in symptoms, with ameliora- 

 tions or aggravations of the symptoms correspond- 

 ing to oscillations of advantage of either body or 

 germ. 



Variations from the type of the stationary period in 

 any infectious disease also occur with a fair degree of 

 frequency. The stationary period may be cut short 

 by the body-forces being marshaled at the onset, and 

 the disease end there ; or it may be prolonged far beyond 

 the average limits for the disease. On the other hand, 

 the microbes may get the upper hand from the start, 

 stifle (in their incipiency) the body's efforts to react 

 and close the picture even before the stationary period 

 had really begun. However, these courses are not 



