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e development of seeds. All the Spermatophyta are heterosporous; fertilization of the egg cell is either through a pollen tube emitted by the microspore or (in a few gymnosperms) by spermatozoids. The phrase "flowering plants" is less distinctive than "seed plants," since the conifers, grasses, sedges, oaks, etc., do n…

The male germ cell in animals and plants, the essential element in fertilization; a microscopic animalcule-like particle, usually provided with one or more cilia by which it is capable of active motion. In animals, the familiar type is that of a small, more or less ovoid head, with a delicate threadlike cilium, or tail…

One of the cells formed by the diivision of the spermospore, each of which is destined to become a spermatozoid; a spermatocyte; a spermatoblast.

The nucleus of the sperm cell.

The protoplasm of the sperm cell. Haeckel.

A mass or ball of cells formed by the repeated division of a male germinal cell (spermospore), each constituent cell (spermoblast) of which is converted into a spermatozoid; a spermatogemma.

The male germinal or seminal cell, from the breaking up of which the spermoblasts are formed and ultimately the spermatozoids; a spermatospore. Balfour.

A sperm cell. Haeckel.

Vegetable tissue composed of thin-walled rounded cells, -- a modification of parenchyma.

, or vertebral, marrow; the myelon. The nervous tissue consists of nerve fibers and nerve cells, the latter being confined to the so-called gray matter of the central portions of the cord, while the peripheral white matter is composed of nerve fibers only. The center of the cord is traversed by a slender canal connecti…

zooids of certain hydroids. They have the form of long, slender tentacles, and bear lasso cells.

One of the cells which, in sponges, secrete the spongin, or the material of the horny fibers.

The formation of reproductive cells or spores, as in the growth of bacilli.

cales; resembling a scale; scaly; as, the squamose cones of the pine; squamous epithelial cells; the squamous portion of the temporal bone, which is so called from a fancied resemblance to a scale.

The solid or insoluble portion of the cell protoplasm. See Hygroplasm.

n; pungent; biting; as, stinging cold; a stinging rebuke. -- Sting"ing*ly, adv. Stinging cell. (Zoöl.) Same as Lasso cell, under Lasso.

One of the minute apertures between the cells in many serous membranes.

wall or face with stones; to line or fortify with stones; as, to stone a well; to stone a cellar.

The deposition of material in successive layers in the growth of a cell wall, thus giving rise to a stratified appearance.

The spongy, colorless framework of a red blood corpuscle or other cell.