Alimentary Canal
2 of the 6 encyclopedias on this shelf carry an entry for Alimentary Canal. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
the digestive tract. In the simplest form, as in the hydra, it is co-extensive with the body-cavity. In the higher animals the alimentary canal is separated from the body-cavity, and there are various enlargements, divisions, and valves in the way of pouches, crops, gizzards, stomachs, and intestines. The study of anatomy and physiology is much simplified if we bear in mind that all these are but modifications of the simple form. The alimentary canal or digestive tract is a tube extending through the body. In the simpler animals, as in the hydra, the process of digestion is carried on within the body-cavity, and there is no tract or tube especially set apart for this work. In the earthworm, however, the alimentary canal is separate from the body-cavity, and consists of a straight tube which is about the same diameter throughout the body. In the higher animals, as in birds and mammals, the tube is much twisted and doubled on itself, so that it is usually much longer than the entire body. In the higher animals, also, it varies in diameter, because of enlargements into pouches, crops, or stomachs. At certain points growths or organs of various sizes, called glands, are connected with it by means of small tubes called ducts. These glands produce and pour into the alimentary canal fluids and juices which aid in digestion. In man the alimentary canal consists of the mouth, the gullet, the stomach, the large and small intestine, and the rectum. Attached to one part of the intestine is the vermiform appendix, a small blind sac, which, when inflamed, is the cause of the disease called appendicitis. See Amoeba ; Sponge ; Earthworm ; Camel ; Bird ; Cud-Chewers ; Ostrich
Collier's New Encyclopedia (1921)
the alimentary tube; the great tube or duct by which food is conveyed into the stomach, and from which the waste and undigested food is excreted. It consists of the mouth, the pharynx (throat), the esophagus (gullet), the stomach, the small intestine, the large intestine, and the rectum, and is about 25 feet long.
What Has Changed in the Last Century
The anatomy Collier's listed in 1921 — mouth, pharynx, esophagus, stomach, small and large intestine, rectum, "about 25 feet long" — is still what students learn. What has changed is everything about what lives and happens inside it: the gut is now known to host trillions of bacteria, the 'microbiome', linked to immunity, metabolism and even mood, and its own dense mesh of neurons, the enteric nervous system, is popularly called the 'second brain'. Aiton's 1910 aside that the appendix is "a small blind sac" of note only when inflamed has softened too; it is now widely thought to serve as a reservoir of gut bacteria. And where stomach ulcers were long blamed on diet and nerves, Barry Marshall and Robin Warren showed in the early 1980s that the bacterium Helicobacter pylori was the culprit, work that won the 2005 Nobel Prize.
Written for this edition, 2026.