The taking of food means very little unless the patient remains in the open air or at least gets enough fresh air to properly oxidize the food. Air is as important for nutrition as food and should really be looked upon as part of the food. So far as possible air should never be rebreathed. Air which has once been breathed is deprived of some of its oxygen and what is still more objectionable is loaded with some of the poisons given off by the body. A tuberculous subject should sit in the open air all day while under treatment and should sleep in a room with the windows open on two sides unless he can do what is better still, sleep out of doors. Even well people should keep their bedroom windows open because what will cure will also help to keep well. There should be no shades or blinds on the windows and houses are better without shutters. Sun and air should be allowed free access to every sleeping room. There need be no fear of draughts. One can sit or sleep in a draught provided he is properly clad or covered.