On the Nervous System. All the effects on the circulation above detailed may often be obtained from digitalis without any serious disturbance of the nervous system; but sometimes the influence of the medicine seems to be early directed to the cerebral centres, even in small doses; and, if the quantity be increased after the reduction of the pulse, or if the same doses be continued undiminished, the nervous symptoms become prominent. The first effect of this kind usually experienced is a sense of weight, or stricture, or slight pain in the head, especially over the brow, which is followed by buzzing in the ears, disorder or dimness of vision, vertiginous feelings, general muscular weakness, and sometimes a tendency to syncope. There is no antecedent mental exhilaration which I have ever been able to discover; and the intellect, instead of being for a time invigorated, as by opium, is weakened, as evinced by the mental confusion, hallucinations, and slight delirium, which often attend the over-action of the medicine. Violent delirium is said to be sometimes induced; but I have never witnessed it. The medicine occasionally causes drowsiness, but this is not an ordinary result. On the contrary, it not unfrequently occasions wakefulness when taken too largely, or acting with unexpected violence in medicinal doses. A feeling of irritation is sometimes experienced in the pharynx and oesophagus, which may be extended to the larynx, giving rise to hoarseness. But among the most frequent effects of over-doses are nausea and vomiting, which are sometimes excessive, and are now and then attended with purging. The nausea and vomiting are to be ascribed more to an operation on the cerebral centres, than directly on the mucous coat of the stomach; for they are said to be produced when the medicine is introduced into the veins, or into the cellular tissue.

Some writers have ascribed these nervous phenomena to a stimulant operation on the nervous centres; but they seem to have lost sight of the well-known fact, that depression and irritation of the cerebral centres often make themselves known by symptoms in many respects identical, and that neither one nor the other condition can be determined by the phenomena which are common to both. But that the condition of the cerebral functions, as of the nervous system generally, is one of depression, may be inferred from the absence of that temporary elevation of the intellectual and emotional functions which characterizes the true cerebral stimulants, from the deficiency of muscular power without anterior increase, from the paleness of face and diminished supply of blood to the brain, and from the general tendency to prostration when the operation of the medicine is in excess.

To the effects upon the nervous centres must be ascribed the remarkable depressing influence of digitalis upon the genital organs, and the sexual propensity, as observed by Dr. Brughmans, of Belgium, and the useful employment of it in certain affections of these organs, as first suggested by M. L. Corvisart, of Paris. But, while such a sedative action is claimed for the medicine upon the generative functions, a power of exciting uterine contraction has also been ascribed to it, of which more will be said hereafter. The chief evidence of its possession of the latter power is afforded by its very happy influence over uterine hemorrhage, as employed by Mr. W. H. Dickinson, in St. George's Hospital, London (Medico-chirurg. Trans., xxxix.); but it cannot be denied that this effect may be ascribed as well to a sedative operation upon the uterine capillaries, as to stimulation of the motor function.

Poisonous Effects

Hitherto I have treated of the effects of digitalis in therapeutic doses. Even from such doses, too rapidly increased or too long continued, the most alarming effects have been frequently experienced, ending sometimes in death. The following are the symptoms usually resulting from a poisonous quantity given at once, or at short intervals. The effects on the stomach and bowels may come on soon after the taking of the poison; those on the nervous system do not generally occur, at least in their greatest intensity, until some hours have elapsed; and it is highly probable that the latter are often in a considerable degree prevented, and life saved, by the evacuation of the poison consequent on the former. Excessive nausea and vomiting with or without purging, griping pains in the stomach and bowels, thirst and dryness of the throat, hiccough, an extremely feeble, small, irregular, and generally slow pulse, paleness of the surface, cold extremities and universal cold sweats, great muscular relaxation and debility, faintness, headache, vertigo, sometimes delirium, perverted vision, insensibility to light, dilated pupil, cramps and convulsions, sunken features, and ultimately coma, are the phenomena ordinarily present in very threatening or fatal cases. A copious flow of saliva has also been observed; but this is a very frequent attendant on nausea from whatever cause. Death usually occurs after a considerable period, in the greater number of cases, probably, between twenty and thirty hours from the taking of the poison. The appearances after death are marks of inflammation in the stomach and bowels, dark and uncoagulable blood, and a loss of contractility in the heart.

The quantity capable of causing death has not been determined. in general, when fatal results have followed one or a few doses of the poison, the quantity known to have been taken has been indefinite, as, for example, draughts of a strong decoction of the leaves, of a handful of the leaves boiled in water, etc. Poisonous symptoms of the most alarming kind have been produced by a drachm of the powder; but the patient recovered. in another case, subsequently reported, death resulted from swallowing, at short intervals, two portions of digitalis, of a drachm each, in the state of infusion. (Edin. Med. Journ., Aug. 1864, p. 1G9, from Gazette des Hopitaux.) in Pereira's Materia Medica, it is stated that a respectable practitioner of Suffolk, England, was in the habit of giving an ounce of the tincture at one dose, and, if he. found no effect at the end of twenty-four hours, of repeating the dose, which then rarely failed to lower the pulse in the desired degree; and this was done not only with safety, but with decided advantage. Sometimes vomiting quickly followed; but never any dangerous symptom. Dr. Pereira himself frequently gave a drachm of the best tincture three times daily for a fortnight, without any marked effect. The tincture, well prepared, contains the virtues of a drachm of the leaves in a fluidounce. These facts are no doubt authentic; but they only prove the great difference of susceptibility to the action of digitalis, and offer no ground for the use of the medicine in so large a dose. I should consider that, after what has been made known of the occasional powerful action of the medicine, a practitioner who should administer an ounce of the tincture at one dose, to an individual not accustomed to its use, would be guilty of manslaughter, should the patient die from the effects of the medicine.*