Elements of the theory and practice of cookery

Section 4. A Lesson in Digestion, illustrated by the Digestive Organs of a Fowl We live not upon what we eat, but upon what we digest. — Meinert. 322. The alimentary canal of a fowl. — When we chop off the head of a fowl we find we have cut through two tubes, one collapsed, the other kept circu- lar by rings of cartilage. The first is the windpipe, the second the " food-pipe," called the esophagus. The latter is part of a long passageway through the body, called the alimentary canal (from aliment, meaning food). To trace the path of this canal, lay the organs drawn from a fowl, as nearly as you can, in the position they occupied in its body, the lungs folded around the heart ; the gizzard in the arched space under the lungs, with the crop close beside the tube leading into the latter ; the liver, with gall-bladder attached, at the left of the gizzard,^ and folded partly around it ; the pan- creas, a slender, yellow body, in the first loop of the intestine, behind and a little below the gizzard. In the fowl the intestines lie in closely packed coils, mak- ing a continuous winding passage from gizzard to vent. See from what a marvellous membrane they are sus- pended, filmy as gauze, yet strong enough to support them. This is the peritoneum. In life another mem- brane, the diaphragm, is stretched between the lungs 1 I.e. on the right-hand side of the fowl's body, as it is in life. 196 THEORY AND PRACTICE OF COOKERY and the organs beneath them, but, when torn, as it is in drawing the fowl, it contracts to a mere strip, almost impossible to find. 323. Comparison of the alimentary canal of a fowl with that of a human being ; why fowls have crops. — If we compare the alimentary canal of a fowl with a diagram of that of a man, we shall find in the latter nothing corresponding to a crop. Why the fowl needs this organ is plain if we examine its month and the sac taken from its gizzard. There are no teeth in the former, but in the latter will be found a number of pebbles. These take the place of teeth; but as food swallowed whole goes down much faster than the giz- zard can grind it up, the crop receives it, and lets only so much pass at a time as the gizzard has room for. In other respects, however, our own digestive organs are similar to the fowl's. Let us trace the course of a mouthful of food undergoing digestion, recalling what we have already learned about the chemical changes taking place in the process (§§ 129, 161, 178, 237, 238, and 292), and using the organs of the fowl to make each step clear. 324. Food in the mouth and esophagus. — In the mouth food is masticated (chewed), and mixed with saliva supplied by three pairs of glands. After being swallowed it is squeezed downward by the contractions of rings of muscle around the esophagus, till it drops into the pouchlike expansion of the alimentary canal called the stomach. 325. Food in the stomach. — The wall of the stomach is of muscular tissue, enclosed in a thin membrane, and lined with another membrane, velvety and moist, that lies, when the stomach is contracted, in soft THE FLESH OF ANIMALS 197