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One of the primary, or first-formed, segments of an embryonic arthropod.

One of the two elongated vibratile young formed by fission of the embryo during the development of certain Gregarinæ.

One of the minute spindle-shaped embryos of Gregarinæ and some other Protozoa.

The embryonic sac of an ovule, sometimes regarded as an innermost fifth integument. Cf. Quartine, and Tercine.

he cotyledons in the seed, and from which the root is developed downward; the stem of the embryo; the caulicle.

in milling. It is dark and of little expansive power, is secured largely from the germ or embryo and adjacent parts, and contains a relatively high percentage of protein. It is chiefly useful as feed for farm animals.

A dicyemid which produces infusorialike embryos; -- opposed to nematogene. See Dicyemata. [Written also rhombogen.]

Very imperfectly developed; in an early stage of development; embryonic.

The embryo produced directly from the egg in a metagenetic series, especially the larva of a tapeworm or other parasitic worm. See Illust. of Echinococcus.

A ripened ovule, consisting of an embryo with one or more integuments, or coverings; as, an apple seed; a currant seed. By germination it produces a new plant.

or pertaining to the segmental organs. Segmental duct (Anat.), the primitive duct of the embryonic excretory organs which gives rise to the Wolffian duct and ureter; the pronephric duct. -- Segmental organs. (a) (Anat.) The embryonic excretory organs of vertebrates, consisting primarily of the segmental tubes and seg…

onucleus. -- Segmentation of the ovum, or Egg cleavage (Biol.), the process by which the embryos of all the higher plants and animals are derived from the germ cell. In the simplest case, that of small ova destitute of food yolk, the ovum or egg divides into two similar halves or segments (blastomeres), each of these…

-- Shell gland. (Zoöl.) (a) A glandular organ in which the rudimentary shell is formed in embryonic mollusks. (b) A glandular organ which secretes the eggshells of various worms, crustacea, mollusks, etc. -- Shell gun, a cannon suitable for throwing shells. -- Shell ibis (Zoöl.), the openbill of India. -- Shell jack…

he wall of the body; somatopleuric; parietal; as, the somatic stalk of the yolk sac of an embryo. Somatic death. See the Note under Death, n., 1.

ry, formerly held by many, that the sperm or spermatozoön contains the germ of the future embryo; animalculism.

An embryo sac or embryonal vesicle in the ovules of flowering plants.

The primitive mouth and esophagus of the embryo of annelids and arthropods.

-- applied to a membrane between the zona radiata and the umbilical vesicle in the mammal embryo.

The cord which suspends the embryo; and which is attached to the radicle in the young state; the proembryo.

A cellular layer derived from the nucleus of an ovule and surrounding the embryo sac. Cf. Quintine.