Whatever thus makes living substance is nourishment; whatever fails to do so is not. If food be taken, and even digested, without being thus assimilated, it becomes an injury to a patient instead of a help. In cases of fever, inflammatory disease, or wasting sores, much rich food feeds the fire. It is like laying rafters on the roof of a burning house for purposes of repair. In such a case small quantities of milk, or milk and hot water (_see_ Digestion), represent the total food which can be effectively used in the body. We write on this subject that in treatment our friends may watch not to injure by making the blood too rich in elements which the system cannot usefully assimilate. Such foods as oatmeal jelly and wheaten porridge will often furnish more real nourishment than pounds of bread, beef, and potatoes. A little careful thought will guide to correct treatment in this matter. An easily assimilated diet is found in Saltcoats biscuits and hot water; many inveterate stomach troubles have yielded to this, when taken as sole diet for some weeks (_see_ Biscuits and Water). Treatment may also be given for lack of assimilative power. The back, especially on either side of the spine, is rubbed with gentle pressure and hot olive oil. This pressure is so applied that a genial heat arises along the whole spinal column. This done twice a day, for half-an-hour at a time, and continued for several weeks, will markedly restore assimilative power. Cases which have been perfectly helpless for eight and even ten years are cured by this simple method, sufficiently and carefully followed. We had a patient who was stout, but weak and weary, with the muscles slack and showing loss of power. The effect of back-rubbing, accompanied by easily assimilated food in small quantities and often, was to lessen his weight by a considerable amount. But the muscular power at once began to increase, and the man was soon like one made anew. Digestion had not been impaired in this case, but the blood formed by it was not converted into good living substance. Sight and hearing have even been restored by these means when the failure in eye or ear has been due to waste material accumulating, as frequently is the case.