ANGIONEUROTIC EDEMA 281 



sensitive involuntary system be subjected to fatigue 

 effects by repeated stimulation, and temporarily be 

 caused to cease functioning. If this be true, the vaso- 

 motor control exercised by the involuntary nervous 

 system and the glands of internal secretion may be 

 seriously impaired or even temporarily lost as a result 

 of nerve end-plate fatigue, produced by repeated or in- 

 tense nervous stimulation or by irritation of whatever 

 sort. 



It is easy to conceive that continuation of a stimulus 

 not sufficiently vigorous at once to exhaust or paralyze 

 a nerve end-plate presently will cause it to become irri- 

 table. In this condition of irritability this nerve end- 

 plate is then nearer to the limit of its endurance than 

 when quite fresh and untired. If it then be subjected to 

 further stimulation it will become totally fatigued 

 sooner or later. The more powerful the stimulation the 

 quicker the complete fatigue. 



Exactly this condition of affairs pertains in every 

 portion of the human body subject to vasodilation and 

 vasoconstriction. Increased wear and tear beyond a 

 certain point, whatever the cause, increases nerve end- 

 plate irritability and lowers its resistance fatigue. That 

 this increased irritability or near-fatigue may be more 

 pronounced in certain parts of the body than in other 

 portions is self-evident. Even different portions of the 

 same structure or same organ, from various causes, 

 may come temporarily to possess different degrees of 

 resistance to fatigue or strain, i. e., may become "tired" 

 to different degrees. In the same structure or organ, 

 therefore, there may exist areas whose vasodilators, not 

 suffering from irritability, respond normally to a given 

 impulse, and which exhibit little flushing and no swell- 

 ing; and other areas whose vasodilators have become 

 supersensitive or irritable, which respond excessively, 

 become reddened and flushed to a marked degree and 

 show evidences of beginning swelling or edematous in- 



