Chapter XII

The factor which brings the expulsive faculty into
action is essentially a condition of the organ or its
contents which is the reverse of that which determined
attraction. Analogy between abortion and normal
parturition. Whatever produces _discomfort_ must be
expelled. That discomfort also determines expulsion of
contents from gall-bladder is not so evident as in the
case of stomach, uterus, urinary bladder, etc., but can
be logically demonstrated.