The fifth division of the oviduct is the _vagina_. There is located, at the juncture of the shell-gland portion with the vagina, a strong sphincter muscle. The vagina is that constricted portion of the oviduct extending from this muscle to the cloaca. The mucous membrane forms low narrow folds with secondary folds, which appear continuous with those of the shell-gland portion. The core of these folds is composed of connective tissue. The vagina in the hen of average size measures from 12 to 13 centimeters long (Surface). The inner or circular muscular layer is well developed; it is much thicker than in any other part of the oviduct. This extra development gives the power necessary to successfully expel the egg. The outer longitudinal layer is not so well developed; its bundles are scattered throughout the connective-tissue layers. The egg is caused to move along in the oviduct by a successive series of contractions of the circular muscular fibers posterior to it. There are no tubular glands in this portion, but a simple layer of high ciliated columnar epithelium, and some goblet, or mucous cells. The cells on the surface generally are long and slender; in the grooves between the mucous folds the cells are shortest, reaching their greatest length at the tops of the folds. The function of the vagina is the secretion, or formation, of the outer shell cuticle commonly called the bloom, and also in certain breeds, as indicated above, the tint. The cloaca furnishes a passage way from the vagina to the external world by way of the anus. The walls of the cloaca contain glands. =The Ligaments of the Oviduct.=—It is held in position by two ligaments, one dorsal and one ventral. The _dorsal ligament_ of the oviduct is formed by a double layer of peritoneum with a very small amount of connective tissue interposed. The peritoneum is also reflected over the oviduct. The ventral ligament of the oviduct is narrower than the dorsal, but is similarly constructed. Both ligaments are rather veil-like in appearance. During the first four or five months of the growth of the young female fowl the development of the oviduct and its ligaments is in proportion to that of the body. With the elongation that takes place about the time of functionation, as described above, the ligaments enlarge in proportion to the enlargements of the oviduct. The dorsal ligament maintains a line of attachment to the body wall from the caudal end of the body cavity to the fourth thoracic rib. The ventral ligament elongates only slightly during this developing period. It becomes thicker and stronger and early develops a muscular coat. It also grows in width except at the caudal end. At this point the ligament is simply a mass of muscular tissue of the smooth or involuntary type. These ligaments are fan-shaped.