In order to control the functions of the various organs and tissues and to regulate the rate at which they reproduce themselves, the nerves extend their terminal branches, not only into every tissue, but into every microscopical unit of such tissue, and the part of the cell which represents the nerve terminal is the inner structure called the nucleus. Now it will be obvious that the more the two nervous systems are worked the greater will be their depletion of _lecithin_ and the more need there will be for fresh supplies of phosphorus in the daily food rations. The person who works hard, whether it be manual labour or brain work, needs food and rest at intervals in order that the nerves may recuperate and replenish their stocks of _lecithin_. A goodly proportion of uncooked foods rich in phosphorus must be supplied to make good the wear and tear, and the digestion must equally be efficient if these food-stuffs are to become assimilated. Cooking of food to a large extent breaks down the organic phosphorus salts and makes them inorganic. In this state they are of but little use to the body. Poor digestion associated with putrefactive fermentation equally converts the organic salts into inorganic ones. These pass into the blood and are promptly eliminated by the kidneys as waste (_phosphaturia_) and thus they never reach the nerves at all. We must remember that phosphorus is usually found in natural foods bound up with the proteid and especially with that proteid which has to do with the reproduction of the species. For this reason man instinctively resorts to the use of egg-yolks, and to the various seeds (such as nuts, wheat, barley, etc.) because of their rich phosphorus content. These proteid-bound phosphorus salts can only be properly utilised when the hydrochloric acid of the stomach juice is well formed, for it converts them into acid salts which are readily absorbed. Therefore to ensure free absorption we must always remember to give the phosphorus-containing foods with such meals as will cause free secretion of the gastric acid. When fermentation is active and the stomach juices are weakened the germs of the intestines rapidly break up the phosphorus constituents of the proteids and make them inorganic. Therefore the first thing to do when a person is found to be suffering from _phosphaturia_ is to stop the intestinal fermentation by a right diet, clear the bowels of their accumulated waste poisons and give the nerves plenty of rest. Another consideration to bear in mind is that the nerves need fat wherewith to build up the _lecithin_. An excessive fermentative sourness of the stomach makes the food so acid when sent into the bowels that the bile, pancreatic and other intestinal juices cannot neutralise them, and so the fats themselves are not emulsified and digested, which fully accounts for the mental depression and debility of which these patients complain.