=Development of the egg.= The method of the formation of an egg is very interesting. It is the same in all birds, but is most conveniently studied in fowls. If a laying hen is killed and the body is opened so that the internal organs can all be seen, one of the most conspicuous of these is a large, convoluted duct having its outlet at the vent. In this duct, which is called the oviduct, are eggs in various stages of formation. At its upper extremity, attached to the backbone, is a bunch of globular yellow substances which are at once identified as yolks of eggs in all sizes. The organ to which these are attached is the ovary. The smallest yolks are so small that they cannot be seen without a powerful microscope. These yolks are not germs, but as they grow the germ forms on one side of each yolk, where it appears as a small white spot. When a yolk is full-grown it drops into the funnel-shaped mouth of the oviduct. Here it is inclosed in a membranous covering, called the chalazæ, and receives a coating of thick albumen. The function of the chalazæ is to keep the yolk suspended in the center of the egg. It does not merely inclose the yolk, but, twisted into cords, extends from either end and is attached to the outer membrane at the end of the egg. After leaving the funnel the egg passes into a narrow part of the oviduct, called the isthmus, where it receives the membranous coverings which are found just inside the shell. From the isthmus it goes into the lowest part of the oviduct--the uterus. Here the shell is formed, and at the same time a thin albumen enters through the pores of the shell and the shell membranes and dilutes the thick albumen first deposited. After this process is completed the egg may be retained in the oviduct for some time. It is, however, usually laid within a few hours. =Rate and amount of egg production.= In the wild state a bird, if not molested after it begins laying, produces a number of eggs varying in different kinds, according to the number of young that can be cared for, and then incubates them. If its first eggs are removed or destroyed, the bird lays more, usually changing the location of its nest. In domestication the eggs of most kinds of birds are removed from the nests daily as laid, and the birds lay many more eggs before they stop to incubate than they do in the wild state.