Frostbite should be treated first by vigorous friction with snow or pounded ice. The affected parts should then be well wrapped with cloths wet with cold water. It is extremely dangerous to bring them near a fire. Afterwards, the part should be wrapped in cotton-wool. _Cholera._ Cholera is a serious acute disease, characterised by frequent watery motions, vomiting, cramp and collapse. _Cause._—It is often contracted by drinking contaminated water. Research has shown the importance of the cholera “carrier,” that is to say the person, usually a native, who harbours in his bowel the specific organism of the disease. He may be perfectly healthy and yet be able to transmit cholera to other people by infecting water or food. The rôle of flies, infected clothes and rags, and faulty conservancy methods must be kept in mind. _Symptoms._—Giddiness, faintness, persistent vomiting and diarrhœa, great prostration, feeble pulse, cold perspiration, colic, intense thirst, and constant desire to pass urine. The vomit and motions rapidly become like rice-water in appearance, and the urine is more or less suppressed. There are severe cramps in the legs, belly, and other parts of the body. If then the pulse becomes weak, the temperature low, and the countenance dusky, the patient will probably sink. On the other hand, reaction may set in, all the symptoms abating, and the pulse, temperature, and colour becoming natural; the water is passed more freely, vomiting is less frequent, and the motions become more natural in colour. _Prophylaxis._—Anti-choleraic inoculations are now practised. They not only afford a considerable degree of protection but lessen the risk of a fatal issue in the inoculated. Hence it is advisable to be vaccinated against cholera whenever there is risk of infection. The inoculation must be repeated after the lapse of four months if the epidemic still persists, as the protection afforded is only temporary. Persons travelling in regions where cholera is present in an endemic form should take a little lactic acid in tea, or add a little vinegar or thirty drops of dilute hydrochloric acid to every ounce of drinking water. At times of epidemic prevalence it is essential that all water should be boiled. The practice of hand-shaking should be discouraged, indigestible diet should be avoided, and raw fruit, raw vegetables, and meat jellies should not be eaten. Lettuces and celery, being moist and eaten uncooked, are specially dangerous. Patients and contact cases must be isolated, and the former should be protected from flies. It is very necessary to maintain a strict supervision of cooks and cooking arrangements. All kitchen cloths should be washed in permanganate solution or boiled. Milk should always be boiled.