By far the most important prophylactic tonic against cardiac neuralgia, however, is arsenic. That this drug should prove useful in cardiac neuroses might readily be anticipated from its very great utility in many cases of asthma, a disease which, as already remarked, has a close relationship to the former. Dr. Philipp has recently recorded a case which is perhaps an extreme instance of this beneficial influence of arsenic, but is none the less encouraging, especially as it only corroborates what has been advanced by other observers. Given in doses of from three to five minims of Fowler's solution, twice or thrice daily, arsenic is an invaluable remedy in cardiac neuralgia; the one objection to it being that some neurotic patients possess such an irritable intestinal canal that the remedy cannot be borne, as it produces diarrhoea. Even here we may sometimes succeed by combining it with very small doses of opium. It is more especially with regard to those cases in which the neurotic character of the disease is very prominent--_i. e._, in which the nervous temperament of the patient betrays itself in other ways besides the tendency to spasmodic embarrassment of the heart's action, that arsenic holds such a very high place as a remedy. And it should be carefully remarked that the prophylaxis of angina extends itself, in such cases, beyond the limits of actually-declared and well-defined angina, which is, of course, an uncommon disease. This remedy is important, and may be most usefully employed in the far larger group of cases in which a marked tendency to spasmodic pain in the chest, on the occurrence of some comparatively trifling excitement, is observed in patients who either have some organic heart-disease, or who are liable to severe attacks of asthma. It cannot be too often repeated that there is no intelligible separation, except one of degree, between these cases and the malignant forms of angina. It may be added that, in my experience, I have found the whole group of cases to be bound together in a singular way by the tolerance of arsenic which, with certain exceptions already referred to, they display. Commencing with the small doses above mentioned, I have found it possible, in many cases, to advance to the administration of twice or thrice the quantity, and to continue this medication for months together, not only with no evil effect, but with the best results. Of zinc, as a prophylactic tonic in cardiac neuralgia, I know but little. Truth to say, it is a nervine tonic of occasional great value, but which, on the whole, I have found so unreliable that I am somewhat prejudiced against it; and perhaps have not given it a fair trial in those milder cases of cardiac pain to which it might be suited. It does appear, however, to have some preferential action on the vagus, and might therefore be possibly more useful than I am at present inclined to think it.