"When thou hast eaten and art full, then thou shalt bless the Lord thy God for the good land which he hath given thee."—Deut. viii.

882. Why does indigestion bring on bilious attacks?

Because the liver secretes a fluid to assist in the digestion of food. The liver is a gland—a similar organ to the glands of the mouth—and it forms bile in the same manner that they form the salivary juice. Only the liver is a much larger gland, and a much greater quantity of blood passes through it. The liver pours its secretion into the biliary duct ([Fig. 49]) to mix with the grey cream as it passes onward, and to further dissolve it. But when the stomach is excited by food which it cannot dissolve, and when the owner of the stomach, disregarding its remonstrances, will persist in over-eating, or in eating things that disagree with the system, then the liver and the stomach sympathise, and the muscular threads, or hands, that prevail all through the alimentary organs, instead of moving onward, move backward, and throw some bile into the stomach to assist to dissolve and remove the excessive or improper food.

CHAPTER XLII.

883. Why does some portion of the food we eat nourish the system, while other portions are useless?

Because most food contains some particles that are indigestible, or that, if digested, are innutritious, and not necessary for the system. The liver is the organ by whose secretion the useful is separated from the useless; for when the bile enters through the duct ([Fig. 49]) and mixes with the grey cream coming from the stomach, it remains no longer a grey cream, but turns into a mass coloured by bile, having upon its surface little globules of milk, small, but very white. Those minute globules of milk (chyle) are the nutritious particles derived from the food; the other portion, coloured with bile, is the useless residue, or rather the bulk from which the nutrition has been extracted.