“Liver Digestion.—­The liver as well as the stomach is a digestive organ, and in a double sense.  It not only secretes a digestive fluid, the bile, but it acts upon the food brought to it by the portal vein, and regulates the supply of digested food to the general system.  It converts a large share of the grape-sugar and partially digested starch brought to it into a kind of liver starch, termed glycogen, which it stores up in its tissues.  During the interval between the meals, the liver gradually redigests the glycogen, reconverting it into sugar, and thus supplying it to the blood in small quantities, instead of allowing the entire amount formed in digestion to enter the circulation at once.  If too large an amount of sugar entered the system at once, it would be unable to use it all, and would be compelled to get rid of a considerable portion through the kidneys.  The liver also completes the digestion of albumen and other food elements.”

TIME REQUIRED FOR DIGESTION.—­The length of time required for stomach digestion varies with different food substances.  The following table shows the time necessary for the stomach digestion of some of the more commonly used foods:—­

min
Rice                       1  00
Sago                       1  45
Tapioca                    2  00
Barley                     2  00
Beans, pod, boiled         2  30
Bread, wheaten             3  30
Bread, corn                3  15
Apples, sour and raw       2  00
Apples, sweet and raw      1  30
Parsnips, boiled           2  30
Beets, boiled              3  45
Potatoes, Irish, boiled    3  30
Potatoes, Irish, baked     2  30
Cabbage, raw               2  30
Cabbage, boiled            4  30
Milk, boiled               2  00
Milk, raw                  2  15
Eggs, hard boiled          3  30
Eggs, soft boiled          3  00
Eggs, fried                3  30
Eggs, raw                  2  00
Eggs, whipped              1  30
Salmon, salted, boiled     4  00
Oysters, raw               2  55
Oysters, stewed            3  30
Beef, lean, rare roasted   3  00
Beefsteak, boiled          3  00
Beef, lean, fried          4  00
Beef, salted, boiled       4  15
Pork, roasted              5  15
Pork, salted, fried        4  15
Mutton, roasted            3  15
Mutton, broiled            3  00
Veal, broiled              4  00
Veal, fried                4  30
Fowls, boiled              4  00
Duck, roasted              4  30
Butter, melted             3  30
Cheese                     3  30
Soup, marrowbone           4  15
Soup, bean                 3  00
Soup, mutton               3  30
Chicken, boiled            3  00

The time required for the digestion of food also depends upon the condition under which the food is eaten.  Healthy stomach digestion requires at least five hours for its completion, and the stomach should have an hour for rest before another meal.  If fresh food is taken before that which preceded it is digested, the portion of food remaining in the stomach is likely to undergo fermentation, thus rendering the whole mass of food unfit for the nutrition of the body, besides fostering various disturbances of digestion.  It has been shown by recent observations that the length of time required for food to pass through the entire digestive process to which it is subjected in the mouth, stomach, and small intestines, is from twelve to fourteen hours.