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Ovule (Name given to that body)

The name given to that body which develops into the seed, after it has been acted on by the pollen. The Ovules are contained in the Ovary (which see) in all flowering plants, except the Coniferous trees and shrubs, the Cycads, so commonly grown in hot-houses, and a few other mostly tropical plants that form the natural order Gnetaceae. The ovary in almost all Phanerogams is closed, so as to entirely conceal the Ovules; but in a few it is open at the top from a very early period.

The Ovules are attached to the placentae to which they are fixed by a stalk, or "funiculus." They are usually very small, and are frequently so translucent as to allow the microscopic structure to be seen, either without special preparation, or, after laying them for a little time in some fluid (e.g., weak solution of caustic potash), to render them more transparent. Others require more elaborate treatment, and must be cut open before they are fit to be examined; but to enter into details would occupy too much space. The description here must, therefore, be restricted to one of the more simple forms of Ovules, afterwards pointing out in what respects, chiefly, other forms depart from this type. The Ovule selected for description is one that remains straight from its earliest appearance till its full maturity, such as is found in the Docks and the Buckwheat. The Ovule first appears like a small, rounded or egg-shaped swelling on the placenta, made up of cells alike in form and contents. This body is usually termed the "nucleus" of the Ovule; but the term "nucellus," now coming into use, is preferable, since "nucleus" should be restricted to the body in the protoplasm of living cells generally known under this name. Round the base of the nucellus a cellular ring soon begins to appear, and continues to grow up to form a thin covering around that body. But, while this has been growing, another covering forms over it also from below upwards, and the two grow till they leave only a minute opening through them at the upper end (i.e., farthest from the placenta), called the "micropyle," which allows the entrance of a slender tube from the pollen grain. The two coverings are named the inner and the outer coats. At the end next the placenta there is, generally, a rarrower neck, or there may be a well-formed stalk, or funiculus; though sometimes there is no visible stalk, the Ovule being sessile, or fixed by a broad base. From the woody, or fibrovascular, bundle in the placenta, a branch runs into the stalk of the