It is wise to seek medical advice in the case of odd or unusual behavior after a fall on the head. CHAPTER XXXV DIET AND NUTRITION Most interesting is the study of the food as it passes through the processes of digestion, absorption, assimilation, and oxidation--all definite and important parts of the great cycle through which everything we eat passes on its way from the table to the tissues. Elimination is the last step in nutrition, and is the process by which the body rids itself of the broken down cells and other poisonous and useless wastes. These various phases of bodily nutrition may be expressed in a single term--metabolism. What we eat and how much we eat must be carefully planned, for our body temple is really made of what we eat. If you were erecting a beautiful mansion you would not think of allowing cheap, trashy, and inferior building materials to enter into the construction of your home. Neither should you permit unfit and inferior materials to become a part of the daily dietary of your little boy or girl, thus to become a part of their bodily structure. ASSIMILATION OF FOOD Following the process of digestion in the stomach and intestine, the nutritive food elements are absorbed through the wall of the bowel by the wonderfully adapted little villus, and distributed by various routes to the uttermost parts of the body. The sugars (all starches are changed into sugar) are carried in the portal blood stream to the liver, where they are actually stored away in the form of glycogen which, in a most intelligent manner, is dealt out to the body from hour to hour as it is needed for fuel. If all the sugar, after a hearty meal, were poured into the circulation at once, the blood stream would be overwhelmed and the kidneys would be forced to excrete it in the urine. This unnecessary waste is avoided by the liver's storing sugar after each meal and dealing it out to the body as required. Likewise, the proteins also pass through the liver on their way to the body. Just what action the liver exerts upon proteins is not wholly known at the present writing. The digested fats are absorbed at once by the lacteals, the beginning of the intestinal lymphatic system, by which they are carried to the large veins at the root of the neck and there emptied into the blood stream. We have now traced our various food elements through the processes of digestion and absorption in the alimentary tract, some going through the liver, and others through the lymphatic system, until they circulate in the blood stream itself. It is from these food substances, circulating in the blood stream, that the various cells of the body must assimilate into themselves such portions as they require for purposes of heat and energy and for the repair of their cell substance. This specialized work of cell assimilation converts the dissolved watery food in the blood into solid tissues, exactly reversing the process of digestion.