The pancreatic duct is the principal excretory duct of the pancreas. It extends transversely from the left to the right through the substance of the pancreas. After leaving the body of the pancreas, it unites with the common bile duct of the liver where it empties into the duodenum (first section of the small intestines after leaving the stomach). The pancreatic duct carries pancreatic juice (a digestive fluid) from the pancreas to the duodenum. =The Spleen.=—The spleen belongs to that class of bodies known as ductless glands and has no excretory duct; is oblong, flattened, soft, very brittle, very vascular, of a very dark bluish red color; is situated in the left hypochondriac region behind and to the left of the stomach; is five inches long, three inches wide and two inches thick and weighs about seven ounces. The vessels which nourish it are the splenic artery and splenic vein. Function. It is supposed to furnish blood corpuscles. [Illustration: FIG. 26—The abdominal aorta and its branches. (Gray)] =The Kidneys.=—The kidneys are large glands, two in number and are situated from five to six inches apart or about three inches on either side of the median line in the right and left lumbar regions. The upper extremity of the kidneys lies on the level of the twelfth dorsal vertebra and the lower extremity on the level of the third lumbar vertebra. Each kidney is four and one-half inches in length, two to two and one-half inches in breadth, a little more than one inch in thickness. The weight of the kidney in the adult male is from four and one-half to six ounces each. In the adult female the weight would be from four to five and one-half ounces. Their function is to separate from the blood certain waste products and an excess of water, the combination of which we know as urine. The principal products excreted by the kidneys from the blood along with water are ammonia and urea. The blood is taken to the kidneys by the renal arteries and the renal veins carry it back to the blood circulation. The urine is then taken from the kidneys by the ureters and conveyed to the urinary bladder. =The Ureters.=—The ureters are cylindrical tubes about sixteen inches in length and of diameter of a goose-quill. =The Suprarenal Capsules.=—The suprarenal capsules belong to that class of bodies known as ductless glands and are two small flattened bodies of yellowish color, situated at the back of the abdomen, behind the peritoneum (the covering for all of the abdominal organs), and immediately above and in front of the upper end of each kidney. The name is derived from the position it occupies in relation to the kidney, supra meaning above, and renal pertaining to the kidneys. The functions are as yet unknown. The suprarenal arteries furnish nourishment for the suprarenal capsules.