Archive image from page 41 of The development of the chick. The development of the chick : an introduction to embryology . developmentofchi02lill Year: 1936 24 THE DEVELOPMENT OF THE CHICK 17/ of the oviduct. The escape of the ovum from the foUicle is known as the process of ovulation. During its passage down the ovi- duct it becomes surrounded by layers of albumen secreted by the oviducal glands. The shell- membrane is secreted in the isthmus and the shell in the uterus (Fig. 5). The ovum is fertilized in the uppermost part of the oviduct and the cleavage and early stages of formation of the
Archive image from page 41 of The development of the chick. The development of the chick : an introduction to embryology . developmentofchi02lill Year: 1936 24 THE DEVELOPMENT OF THE CHICK 17/ of the oviduct. The escape of the ovum from the foUicle is known as the process of ovulation. During its passage down the ovi- duct it becomes surrounded by layers of albumen secreted by the oviducal glands. The shell- membrane is secreted in the isthmus and the shell in the uterus (Fig. 5). The ovum is fertilized in the uppermost part of the oviduct and the cleavage and early stages of formation of the germ-layers take place be- fore the egg is laid. The time occupied by the ovum in tra- versing the various sections of the oviduct is as follows: Glandular portion of the ovi- duct three hours, isthmus one hour, uterus and laying sixteen to seventeen hours (combined observations of Patterson, and Pearl and Curtis). If the hen be disturbed eggs may be re- tained long after they are ready to be layed. Some of the details of these remarkable processes deserve attention: the observations of several naturalists demonstrate that the ripe follicle IS em- FiG. 5. — Uterus (shell-gland) of the hen cut open to show the fully formed egg. (After Duval.) 1, Cut surface of oviduct, region of isthmus. 2, Reflected flap of uterus, uopprl bv thp funnpl of tho ovi- 3, Egg ready to be laid. 4, Lower 'iacea Dy me lunnei 01 ine OVl extremity, or vaginal portion, of the duct before its rupture SO that oviduct. 5, Rectum. 6, Opening of xr ovum dopq not psrnnp into the oviduct into the cloaca. 7, Open- ovum aoes not escape mto ing of the rectum into the cloaca. 8, the body-cavity, but into the °' oviduct itself. Coste describes the process in the following way: ''In hens killed seventeen to twenty hours after laying I have observed all the stages of this re- markable process. In some the foUicle, still intact and enclosing its egg, had already been swallowed, and the mouth of the oviduct, cont
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