Hallucinations also occur in the decline of the disease, dur-
ing the period of convalescence. First they appear singly, in
association with those of the fever, and are often recognized
by the patient as such and concealed from those around him.
But soon they overm^tster the sufferer, and delirious states are
developed, or states resembling hallucinatory insanity, in
which visions of corpses, death's-heads, mocking voices, and
offensive olfactory and gustatory hallucinations play a part.
Of an equally distressing nature are most of the sensory
fallacies of collapse-delirium, and those which sometimes pre-
cede death. In tuberculosis, on the other hand, they are often
of an agreeable nature, corresponding to the euphoria which is
so characteristic of this disease. — (Pp. 46-50.)

The most frequently quoted of all sense-deceptions are those
of insanity. Some authors have sought to divide them accord-
ing to their origin into "idiopathic," those which are primary
but which may also occur in secondary consensual morbid
states, and "symptomatic," those which occur only as a sec-
ondary symptom of insanity. In any case a distinction ought
to be drawn between sporadic hallucinations not associated



33> TRUTH AND ERROR -

with pardenkr emotional states, and hallndnations which
reflect the ruling mental tone. This distinction has prog-
nostic importance, since observation seems to prove that hallu-
cinations depending on certain morbid emotional states are
capable of disappearing with them, whilst independent hallu-
cinations seldom admit of cure, and pass over into the state of
secondary psychical weakness.
