If the diarrhœa is persistent, an astringent is needed: five grains of tannin, or two or three grains of sulphate of iron may be given three times a day. Ten grains of quinine should be given each day. All food should be semi-solid and tepid; milk diet, as recommended below for enteric fever, is the safest food, but soup thickened with rice or arrowroot is good. The patient should keep in bed and wear a flannel band round the belly. Sometimes in the tropics, as the result of excessive purgation, diarrhœa is very acute and may be alarming. In such cases a hot bath, stimulants and the administration of astringents are indicated. If the trouble continues for more than a few days it is probably due to dysentery, or typhoid. _Diphtheria._ Diphtheria is an acute infectious disease, the essential feature of which is a peculiar inflammation of the lining membrane of the mouth, nose, throat, and windpipe, characterised by the formation of a membrane upon the inflamed surface. Diphtheria occurs in the tropics but happily does not spread much in hot countries. _Causes._—It may be contracted from some person suffering from the disease, from a healthy “carrier” harbouring the specific micro-organism (_Bacillus diphtheriæ_) in his throat or nose, or from infected milk, etc. As the disease is a very grave one, and skilled treatment is often an absolute necessity, measures should be immediately taken to summon medical assistance on the first appearance of diphtheria, or the patient should be sent as speedily as possible to a place where medical aid is likely to be obtained; for if the breathing becomes so difficult that the patient gets blue in the face, an operation for opening the windpipe will be necessary. Incubation period, two to six days or even longer. _Symptoms._—Headache, discomfort, loss of appetite, sore throat, and sickness, with swelling of the glands at the angle of the jaw. On examination the palate and tonsils are seen to be swollen, with a white deposit of membrane upon the surface. The membrane may be thick and tough, and if stripped off will leave numerous small bleeding points. The temperature may run up, and is irregular in type. The pulse is rapid and feeble, and the bodily strength is quickly lost. If the nose be affected there is copious discharge from the nostrils, with difficulty of breathing and much discomfort. If the windpipe is affected the voice will become hoarse or absent, and there will be greater difficulty in breathing, accompanied by a loud crowing noise. Diphtheria may be accompanied by cough and pneumonia. _Treatment._—Isolation. Bed. If diphtheria anti-toxin is obtainable, it should be administered at the earliest opportunity, but this should only be carried out by a doctor.