The succession of symptoms occurring in a case of biogony constitutes its course. Instead of the wild disorder and confusion one would expect under the "attack" theory of "disease," these developments are regular, orderly and follow a more or less definite plan.

Symptoms are classed as follows:

Clinical symptoms are those seen by the doctor at the sick bed or clinic. Pre-clinical symptoms are those that occur from time to time before the doctor is called or visited. Pre-conscious symptoms are those functional and structural impairments which precede and lead up to the pre-clinical symptoms, and of which the individual is not conscious. (The impairments, at their beginning, are not discoverable by any known means of examination, or by any present-day test). Terminal symptoms are those gross structural changes and functional failures which represent the endings or final developments in the degenerative process. Some of these are seen during the life of the patient, but they have been most carefully and minutely studied in the necropsy room. A prodrome is a forerunner or sign of "disease," while the period of the prodromes is called the