Bile
2 of the 6 encyclopedias on this shelf carry an entry for Bile. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
in physiology, one of the digestive fluids. Bile is a thick, golden brown liquid of bitter taste and having an alkaline reaction. It is manufactured from the blood in the cells of the liver. The liver of an adult produces about a quart daily. The bile passes from the liver directly into the duodenum, or, if not needed for immediate use, it is stored in the gall sac, to be drawn upon later. Bile is an important digestive juice. It aids in breaking down fats, thereby assisting in their digestion. It separates the proteids so that they can be acted upon by the ferment, trypsin. It takes part in converting chyme into chyle. Bile is thought by many medical authorities to prevent in some degree, at least, the putrefaction of food. One of the functions of the liver is the destruction of certain poison-producing bacteria that flow into it with the blood. These the liver kills and sends on into the duodenum with the bile. If the process of bile production is interrupted, the destruction of the bacteria ceases. The bacterial poisons increase in the system and show their presence by coated tongue, by headaches, dullness, loss of appetite, and other conditions called in general biliousness. Yellow biliousness is due, therefore, to a lack of bile, not an excess. Certain drugs, well known to the medical profession, have the quality of increasing the supply of bile. They are prescribed, accordingly, for biliousness.
Collier's New Encyclopedia (1921)
an animal fluid secreted by the liver. It is collected from venous and not from arterial blood. It is a viscid, transparent liquid of a very deep yellow or greenish color, darkening by exposure to the air. Its odor is disagreeable; its taste nauseous and bitter. It has an alkaline reaction. When the bile is elaborated in the liver, it is received from the secreting vessels by very minute tubes, which, uniting, form the hepatic duct. The bile is conveyed into the gall bladder by means of the cystic, or into the duodenum by the choledoch duct; that which makes its way into the former receptacle is called the cystic bile, and that which enters the latter the hepatic bile. Cystic bile is deeper in color and more viscid, pungent, and bitter than hepatic bile. One main use of bile is to convert chyme into chyle as one step in the process of digestion.
What Has Changed in the Last Century
The physical description holds up: bile is still a bitter, alkaline, greenish-gold liver secretion, stored and concentrated in the gall bladder, and it still emulsifies fat. Almost everything Aiton's built on top of that in 1910 has gone. "Biliousness" — coated tongue, headache and dullness explained as bacterial poisons escaping an idle liver — belongs to the autointoxication theory that medicine abandoned in the 1920s and 1930s; bile does not "separate the proteids" for trypsin, and the chyme-into-chyle language both entries use has dropped out of physiology. What replaced it is chemistry: bile acids are made from cholesterol, the golden-brown color comes from bilirubin left over from broken-down red cells, and since the late 1990s bile acids have been recognized as signaling molecules acting on receptors such as FXR, with drugs designed against them. Gallstone disease, meanwhile, is now routinely handled by laparoscopic cholecystectomy, standard since about 1990, and people live normally without a gall bladder at all.
Written for this edition, 2026.