The opinion has recently been put forth by Dr. Fuller, of London, and has received the support of several writers, that digitalis, so far from being sedative to the heart, is in fact tonic in its influence on the cardiac muscular fibres. This opinion is founded mainly on the fact that digitalis proves most useful in those cases of disease of the heart in which that organ is dilated and enfeebled; and that, instead of further weakening the heart, it gives greater energy to its actions. But I believe that this view is incorrect; and that its advocates have been led into error by confounding depression of action with diminution of power. Those who maintain the sedative action of digitalis upon the heart, do not maintain that it has the property of directly diminishing the power of that organ. On the contrary, it may even increase the strength of a diseased heart indirectly, by diminishing its action. in reducing the frequency of the heart's action it operates through the nervous centres, and not directly on the heart itself. it is, therefore, depressing or sedative to the cardiac actions, without immediately affecting the organ. The effect of morbidly increased action on a heart already weak is to increase its weakness by exhaustion. Whatever, therefore, depresses this excessive action, without immediately acting on the heart, prevents its further exhaustion under the over-exertion, and gives it an opportunity to recover its powers partially through comparative rest. Thus digitalis may indirectly strengthen the heart, while acting as a sedative to its function. The idea that it is really tonic to the heart is a very dangerous one, as it may lead to its use under circumstances where it can do only harm; that is, to cases in which the heart may be greatly debilitated and yet not overexcited, where not only the heart is weak, but the pulse is slow and also weak. According to Dr. Fuller, and the advocates of his hypothesis, digitalis proves fatal by a tonic contraction and spasm of the heart; and in support of this opinion, the asserted fact is adduced that in death from this poison the heart has been found contracted and empty, and its orifices constricted. Now the fact is that, in the recorded cases of poisoning by digitalis, the pulse becomes gradually less and less frequent, and more and more feeble till the close; and all the general symptoms are those of great prostration, to be obviated only by powerful stimulation. Though a heart acting with morbid frequency may be at first indirectly strengthened by reducing its excitement, yet, if the medicine is given in poisonous doses, the actions are reduced to a point at which the heart ceases to be adequately supplied with blood in its own tissues, and becomes therefore completely prostrated. The constriction of the heart and orifices after death has yet been observed in too small a number of instances to justify any conclusions from it. The idea that the orifices are constricted by its operation is contradicted by the greater fulness of the pulse, which, according to my own observation, very often, if not generally, accompanies a reduction in its frequency under the remedial action of the medicine; a result simply owing to the larger amount sent out by the contractions severally when their number is diminished. The idea of its tonic property is supposed to be supported also by its favourable influence in delirium tremens, in the last stages of which the pulse is often extremely feeble; but here, as in cardiac disease, it acts by simply reducing action and not diminishing power. its supposed contractile influence over the uterus has also been adduced in support of the idea of a contractile power over the heart; but it does not seem to me that any such relation as this can be claimed for the two organs, unless it could be shown that they have the same nervous centre. With Dr. Fuller I agree fully in believing that digitalis does not act by paralyzing the muscular fibre of the heart; but this does not require the admission of the hazardous idea that it is tonic to the organ. it operates simply, as before stated, by depressing the action of the nerve centres which regulate the heart's action.

On the Respiration. The depressing effect of the medicine upon the respiratory function, though shown, by the experiments of MM. Bouley and Reynal upon the horse, to accompany in that animal the similar influence on the circulation, has not been so satisfactorily established in reference to man. Experiments upon the subject have led to the conclusion, that the function is sometimes accelerated, but more frequently diminished; and it would seem that the simple reduction of the heart's action ought to be followed as a necessary consequence by that of respiration. (MM. Homolle and Quevenne, ut supra, p. 316.)

On Temperature. There does not appear to be much more certainty as to the effects of the medicine upon the temperature of the body. While MM. Dumeril, Demarquay, and Lecointe found the temperature increased eight times and diminished once in dogs, MM. Bouley and Reynal have noticed a diminution of it in horses from therapeutic doses (ibid., p. 236), and Dr. Traube states, as the result of his observations, that it lowers the temperature in febrile and inflammatory diseases. (Arch. Gén., 4e sér., xxviii. 338.) in relation to the first series of experiments, it should be stated that they were made with doses of fifteen or more grains of the-extract of digitalis; so that, as with the similar experiments with poisonous doses on horses, it might be expected that the temperature should be raised, like the circulation, through the sympathetic effect of the irritation of stomach, before the proper influence of the medicine on the nervous centres could be obtained. So far as I have myself noticed the effects of digitalis in this respect, they correspond with the observations of Dr. Traube. There is no doubt that, in the cases in which it produces great depression of the circulation, with nausea and vomiting, it reduces the temperature in a corresponding degree.