g6 Course of Disease. 



diseases which ordinarily continue for a year or more, a shorten- 

 ing of the course to a few months manifestly fixes such duration 

 as an acute one, as in case of tuberculosis, glanders or rickets. 

 [The terms acute and chronic have really a less, limited signifi- 

 cance than the author here applies to them ; they each have in one 

 sense a reference to the length of the course, but in addition refer, 

 perhaps without desirable clearness, to the possibility of recovery 

 and the intensity of symptoms and the order of events in the 

 course. In the matter of time it is scarcely possible to give any 

 fixed number of days, or even months, to the terms. Each dis- 

 ease is a law unto itself, and only in the broadest way may we 

 say that an acute course is one of brief duration. But in addi- 

 tion, when we apply this term, we mean that whatever the actual 

 duration, at any rate the disease will come to a definite Umit ; and, 

 moreover, w^e expect the course to follow more or less closely a 

 given order in the manifestation of its symptoms, and believe 

 there is a chance of recovery. In case of chronic diseases again 

 we cannot set a fixed limit of days, months, or even years, which 

 shall declare the course to be a chronic one. (Thus, while alienists 

 are inclined to set a limit of a year to cases of mania or melan- 

 cholia, and to call all cases chronic if of longer duration, there 

 really are no appreciable dififerences in many instances of even 

 longer duration from their condition within the first few weeks of 

 insanity.) Moreover, when a case is declared chronic, while 

 there is no actual assertion to this effect, nevertheless there is a 

 feeling of hopelessness as to the chance of recovery ; the termina- 

 tion looked for is rather death, and that at an indefinite time. No 

 exact order of symptom presentation is expected in such chronic 

 cases. Finally, while there are often exceptions to this point, 

 in general the severity of the symptoms of an acute case is apt to 

 be greater than in a chronic form of the same disease.] 



Diseases often show [especially those of an acute, regular or 

 definite type of course] a succession of definite periods or 

 stages in which certain phenomena appear, which are empirically 

 expected and whose development is awaited with the progression 

 of the anatomical changes. These diseases are said to have a 

 typical course. [A regular or definite course is well illustrated by 

 the acute infectious fevers, in which the following periods may 

 be recognized in the order named: (a) infection (time of en- 

 trance of the microbic cause), (b) incubation (a period without 

 symptoms, l)ut during whicli the .germs are multiplying in the 



