The medical man who contents himself with merely ordering certain medicines, and who does not at the same time regulate the patient's diet, neglects to avail himself of a most valuable auxiliary, and may be allowing the presence of an antagonist, which, in all probability, will counteract all the benefit that might otherwise be reasonably expected to result from his prescriptions. Who, for instance, can expect benefit from antiphlogistic medicines, so long as a full animal diet, with wine and stimulants, is simultaneously pursued? and can we be surprised at the failure of a course of tonics, if only weak slops and an antiphlogistic diet be followed? A stimulant diet notoriously interferes with the action of Mercury. Salt meat, and other substances taken with much salt, are likely to retard the operation of the Nitrate of Silver; whilst in many cases Iodine is rendered almost inert, by being conjoined with a diet of which amylaceous substances form a large part. The diet should in every case be regulated so as to promote, as far as possible, the operation of the medicines which are being employed at the time. Many instances are on record, in which well-directed medical efforts have been frustrated, by the patient indulging in food or drink without the sanction of his medical adviser. Recamier mentions, that in the treatment of cancer, he found Conium exercised a very powerful influence, if the patient were placed on a very low vegetable diet, but that its action was hardly observable whilst a full animal diet was taken. May not a forgetfulness of this fact be one of the causes why this drug, formerly held in high esteem, so frequently fails in cancerous cases at the present day Another example of the influence" of diet is mentioned by Dr. Rust. Having observed the great success with which his friend, Dr. Von Zellenberg, treated Syphilis with Hydrochloric Acid, he resolved to make a trial of its virtues. He accordingly employed it in several instances, and, to his astonishment, it failed to produce the slightest benefit in a single patient. On investigating the subject more closely, he found that Von Zellenberg kept his patients on a very low scale of diet, whilst he had omitted to place any restriction of the kind. He followed his friend in this particular also, and, like him, was successful in his practice. I may add an example which occurred in my own experience. In my first trials with the Sulphate of Iron in Intermittents, I administered it only to the Burmese, and the benefit which attended its use was, in the majority of cases, very marked and unequivocal. I administered it subsequently to the Hindoo and Mussulman Sepoys, and, to my dismay, it failed to produce any benefit. On investigating the cause of this, I found that, whilst the Burmese rigorously abstain from vegetable acids during an attack of fever, the Sepoys indulged in them to a great extent. Having prohibited the use of acids by the latter, I found that the Sulphate of Iron exercised the same influence on them as it had previously done on the Burmese. These instances, without adducing others, are sufficiently illustrative of the importance of regulating the diet of the patient. The medical man, moreover, should not be content with simply giving directions on the subject of diet, but he should see that his instructions are followed out.

* Edin. Med. Surg. Journal, vol. v. p 141.

8. The period of the day at which medicines are administered modifies their operation. Narcotics operate most favourably if given an hour or two before the time at which the patient usually retires to rest, sufficient time being allowed for the stage of excitement to pass over. Emetics are best given towards night, so that the sleep which usually supervenes on their use may be the more readily indulged. Diaphoretics are, likewise, administered with the greatest advantage at the same period, the circumstances of warm bed-clothes, a horizontal position, and an equable temperature, favouring their operation. On the other hand, diuretics are best given during the day, when the surface of the body can be kept moderately cool. Aloes and the resinous cathartics, which remain a long time in the intestines previous to their action, are best given at bedtime; their solution will then be completed, and their operation will commence on the following morning: but the other cathartics, as the neutral salts, Senna, Castor Oil, &c, whose operation is speedy, should be given early in the morning, on an empty stomach. As a general rule, cathartics should not be given so as to interfere with the patient's regular rest. The administration of medicines with reference to the periods of taking food, also requires the attention of the practitioner: thus. Quinine acts most powerfully if given on an empty stomach; Arsenic, most beneficially if given directly after a full meal; antacids, if taken four or five hours after a full meal, when we may suppose the digestive process to be nearly completed; Iodine should not be given immediately after meals of arrow-root, sago, &c., or of substances abounding with starchy matters; and the operation of an aperient is materially interfered with, by being taken on a full stomach. If copious draughts of diluents be taken soon after a dose of Dover's Powder, or of any of the preparations of Ipecacuanha, or after fractional doses of an antimonial, vomiting is likely to be produced, and the medicine to be ejected, without performing its proper office, unless, indeed, it has been given with a view of acting as an emetic.

9. Light, Air, and Exercise influence the action of medicines more than is generally allowed. They very sensibly promote the action of tonics and alteratives, particularly that of Iron and of Iodine; indeed, taken alone they tend in no inconsiderable degree to invigorate the constitution, to give tone to the digestive organs, and energy to the nervous system. Confinement in close, dark, ill-ventilated apartments, effectually counteracts any beneficial influence which might otherwise be derived from tonics, and renders the patient languid, sallow, unhealthy, scorbutic, or dropsical. On this point, Dr. Ranking * observes that scrofulous patients who are not able to walk, should sit in the open air; anything is better than to pass the chief part of the day in the confined air of a sick-room, or hospital ward. "This is a point," he adds, "which I would strongly urge upon the attention of all who have the care of scrofulous cases, as I feel convinced that, in many instances, the failure of Iodine is due to the neglect of insisting, at the same time, upon the patient taking exercise in the open air." This opinion few medical men will be inclined to dispute. Exercise, without doubt, retards the operation of narcotics, even when taken in poisonous doses. An illustrative case is related in Lockhart's "Life of Sir Walter Scott." A young farmer swallowed a quantity of Laudanum in mistake for some other medicine. While all around him were stupid with fear, he rose, saddled his horse, and rode to the doctor's residence, six or seven miles, and did not feel the operation of the drug until he had alighted, when it instantly began to operate. He perfectly recovered. Exposure to the sun is said to hasten the production of that peculiar blueness of the skin, which occasionally appears during a prolonged course of the Nitrate of Silver. The action of diuretics is retarded by exercise in the open air, whilst that of Digitalis is frequently not observed under the same circumstances.

* Translation of Lugol on Scrofula, p. 242. Vol. v. p. 186.