Trigger

(trig'-er). A device by means of which a catch or spring is released. T.-area, a sensitive region of the body, irritation of which may give rise to certain peculiar phenomena, either physiologic or pathologic, in some part of the body. T. -finger, a condition in which flexion or extension of a finger is at first obstructed, but finally accomplished with a jerk or sweep. T.-material, an apheter; any theoretic cat a static substance whose sudden breaking up communicates an explosive decomposition to the protoplasm directly concerned in any function. The trigger-material itself must be acted upon by another trigger-material; and thus every nerve-impulse and every functional act must be accompanied by the destruction of a fuse-like train of protoplasm. See Apheter .