re excessively prolonged wakefulness,
caffein may be used as the most powerful agent known for producing
wakefulness. In a series of experiments, J. Hughes Bennett found
that within narrow limits there is a direct physiological
antagonism between caffein and morphine. Coffee and caffein in
narcotic poisoning are of value as a means of keeping the patient
awake, and of stimulating the respiratory centres.

As a cardiac stimulant, caffein may be used in any form of heart
failure; the indications for its use are those which call for the
employment of digitalis. It is superior to digitalis in never
disagreeing with the stomach, in having no distinctive cumulative
tendency, and in the promptness of its action. It is pronouncedly
inferior to digitalis in the power and certainty of its action, and
in the permanence of its influence once asserted. As a diuretic it
is superior; it is very valuable in the treatment of _cardiac
dropsies_, and is often useful in _chronic Bright's disease_ when
there is no irritation of the kidneys.

On account of its tendency to produce wakefulness, it is usually
better to mass the doses early in the day, at least six hours being
left between the last dose and the ordinary time for sleep. From
eight to fifteen grams (of caffein) may be given in the course of a
day in severe cases. If tried, it would probably prove a useful
drug in cases of _sudden collapse_ from various causes.

Good effects of coffee are recounted by Thompson.[237]

It removes the sensation of fatigue in the muscles, and increases
their functional activity; it allays hunger to a limited extent; it
strengthens the heart action; it acts as a diuretic, and increases
the excretion of urea; it has a mildly sudorific influence; it
counteracts nervous exhaustion and stimulates nerve centers. It is
used sometimes as a nervine in cases of migraine, and there are
many persons who can sustain prolonged mental fatigue and strain
from anxiety and worry much better by the use of strong black
coffee. In low delirium, or when the nervous system is overcome by
the use of narcotics or by excessive hemorrhage, strong black
coffee is serviceable to keep the patient from falling into the
drowsiness which soon merges into coma. In such cases as much as
half a pint of strong bla