sted, its improved vigour being really due to its obtaining a larger
supply of the nutrient blood. Almost equally striking is the fact that
digitalis causes an irregular pulse to become regular. Added to the
greater force of cardiac contraction is a permanent tonic contraction of
the organ, so that its internal capacity is reduced. The bearing of this
fact on cases of cardiac dilatation is evident. In larger doses a
remarkable sequel to these actions may be observed. The cardiac
contractions become irregular, the ventricle assumes curious
shapes--"hour-glass," &c.--becomes very pale and bloodless, and finally
the heart stops in a state of spasm, which shortly afterwards becomes
rigor-mortis. Before this final change the heart may be started again by
the application of a soluble potassium salt, or by raising the fluid
pressure within it. Clinically it is to be observed that the drug is
cumulative, being very slowly excreted, and that after it has been taken
for some time the pulse may become irregular, the blood-pressure low,
and the cardiac pulsations rapid and feeble. These symptoms with more or
less gastro-intestinal irritation and decrease in the quantity of urine
passed indicate digitalis poisoning. The initial action of digitalis is
a stimulation of the cardiac terminals of the vagus nerves, so that the
heart's action is slowed. Thereafter follows the most important effect
of the drug, which is a direct stimulation of the cardiac muscle. This
can be proved to occur in a heart so embryonic that no nerves can be
recognized in it, and in portions of cardiac muscle that contain neither
nervecells nor nerve-fibres.

The action of this drug on the kidney is of importance only second to
its action on the circulation. In small or moderate doses it is a
powerful diuretic. Though Heidenhain asserts that rise in the renal
blood-pressure has not a diuretic action per se, it seems probable that
this influence of the drug is due to a rise in the general
blood-pressure associated with a relatively dilated condition of the
renal vessels. In large doses, on the other hand, the renal vessels also
are constricted and the amount of urine falls. It is probable that
digitalis increases the amount of water rather than that of the urinary
solids. In large doses the action of digitalis on the circulation causes
various cerebral symptoms, such as seeing all objects blue, and various
other disturbances of the special senses. There appears als