Cholecystographic examinations of a normal human being show the gall-bladder outline, frequently the cystic duct, and occasionally the common bile duct. I wish to present a case in which the roentgenograms show the entire biliary system, with the exception of the bile capillaries. In order to refresh the reader's memory concerning the biliary system, the anatomic study is briefly reviewed. Biliary Tract Anatomy The liver consists of two main lobes, the right and the left, each composed of small individual parts called lobules which are held together by extremely fine areolar tissue. The size of the lobules are from 1 to 2.5 mm. in diameter, and each lobule consists of a mass of cells called the hepatic cells which secrete the bile. The biliary ducts, which convey the bile, originate in the little passages in the liver cells which communicate with canaliculi, termed bile capillaries or inter-cellular biliary passages. These passages are merely small channels or spaces left between the contiguous surface of two cells or in the angle in which three or more liver cells meet. The channels thus formed radiate to the circumference of the lobule and open into the interlobular bile ducts which accompany the portal vein and the hepatic artery. These join like the twigs and branches of a tree to eventually form two large main biliary ducts, the right and left hepatic ducts,2 nearly of equal size, and which issue from the liver at the porta hepatis, one from the right, the other from the left lobe.3 These unite to form the hepatic duct, which passes downward and to the right, for three or four centimeters, where it is jointed at an acute angle by the cystic duct from the gall bladder and forms the common bile duct. The common bile duct is about seven centimeters long and normally about three millimeters in diameter. At the termination, it unites with the pancreatic duct and opens by a common orifice upon the summit of the duodenal papilla, situated on the medial side of the descending portion of the duodenum. The short tube, formed by the union of the two ducts, is dilated into the ampulla of Vater. The cystic duct, about three to four centimeters long, runs backward and to the left from the neck of the gall bladder to join the hepatic duct. The mucous membrane lining its interior is thrown into a series of from five to twelve crescentric folds, similar to those found in the neck of the gall bladder, which project into the duct in regular succession. These resemble in appearance a continuous spiral valve and are called the valves of Heister. Sherwood Moore's Comments Recently, following the oral administration of opaque dye to a patient, the entire biliary duct system was visualized with the exception of the bile capillaries. This observation appeared so unusual that the findings were communicated to Dr. Sherwood Moore, radiologic co-worker of Dr. Graham and Dr. Cole, discoverers of cholecystography.