It has been very generally supposed that alcohol acts as a stimulant upon the heart, increasing the frequency and power of its beat. The matter has been much debated, and many experiments have been made with a view to ascertain what the effect of alcohol on the heart-beat really is. In a recent survey of the whole question the conclusion arrived at is that "it has yet to be proved that the heart-muscle can be stimulated by alcohol."2

Most of the observers, however, agree that an increase in the pulse-rate, lasting about half an hour, follows the taking of a moderate dose of alcohol, and there seems to be no doubt that this does commonly occur, although not always. In Higgins's investigation on the respiratory activity, quoted above, a slight quickening of the heart-beat was recorded in about one-half of the experiments; no change was detected in the other cases. Apparently different persons react differently to alcohol, in this respect as in others. Probably also the quantity taken and the degree of dilution have some influence on the result.

There is reason to believe, however, that this quickening of the pulse, where it occurs, is not in the main due to a direct action of alcohol on the heart, since most of the observations made on the isolated heart, free from nervous control but still beating, have shown no quickening or strengthening of the beat under the influence of alcohol. It has been suggested that the accelerating effect noted above is probably an indirect result of alcohol acting on the nervous inhibitory centre which restrains the heart-beat, and weakening that restraint. The quickening effect has been observed when fairly strong alcohol (50 per cent.) has been simply placed in the mouth and rejected, without being swallowed.

A single dose of fairly strong alcohol, such as brandy, may produce useful reflex effects in cases of fainting or syncope, causing the heart to beat more rapidly. But as regards this it has been urged that the mere act of swallowing, even if the liquid is only water, produces a similar reflex action. Alcohol perhaps acts simply by virtue of its irritant action on the mucous membrane of the mouth and throat, much in the same way as the fumes of ammonia, or of ether, or of burnt feathers, will act as an irritant or stimulant when inhaled. That the effect is a local and indirect one is evidenced by the fact that it appears almost at once, before there has been time for any significant quantity of alcohol to be absorbed and carried to the heart. In other cases, where there is more protracted weakness of the heart, a beneficial effect of alcohol is attributable to its narcotic and sedative action on the nervous centres which affect the action of the heart.

1 Loc. cit., p. 70.

2 " Alcohol and the Cardio-Vascular System," by Drs. Munro and Findlay, of Glasgow Royal Infirmary.

Alcohol when swallowed produces a general relaxation of the small arteries which carry blood to the skin. It thus causes a slight general flushing of the body surface. It appears, however, to have only a small and not very definite effect upon the arterial blood-pressure. A small rise of pressure has been detected by some observers after intravenous injection of alcohol; others have noted either a slight fall, or no definite effect.