Carbohydrates, absorbed as glucose or other monosaccharids, are carried by the portal blood to the liver, and thence passed into the blood, to be burned in the muscles, if needed for fuel, or stored tem-porarily in the liver and muscles as glycogen (a polysaccharid yielding glucose) for future conversion to sugar when required as fuel.

Fats, passing through the intestinal wall as fatty acids and glycerol, enter the lymph largely as fat again, and finally pass to the blood to be burned in the muscles for fuel, or to be stored as fat until needed.

Proteins pass into the blood as amino acids. Those needed for building material are taken up by the cells (especially cells of the muscles) and those not required for this purpose are freed from their nitrogen (in the liver or muscles) and then burned for fuel.

For a fuller discussion of the fate of the absorbed foodstuffs see Chapter IV (Food Preparation, The Principles And Technique) of Sherman's "Chemistry of Food and Nutrition."