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- 
