embryon atæ

pl. [Mod. Lat., from Gr. the yolk-bag, below the embryo, from the general embryon=an embryo (q. v.); Lat. fem. pl. adj. suff.. cavity. The amnion (q. v.) and allantois (q. v.) are then formed, the chief office of the latter being to convey the ve els of the embryo to the chorion (q. v.). Then comes the respiratory proce (q. v.). (EGG, CIRCULATION, FOETUS.] 2. Animal Phys .: In the higher vertebrates the development presents an analogy to that described under 1. At a later period the human and higher animal embryo is called a Fœtus (q. v.). 3. Veg. Phys.: The rudiments of the future plant contained in all true seeds, not in spores. In some seeds the embryo constitutes nearly the whole of the structure, in others it is embedded in albumen. In a perfectly developed embryo there are three parts, a cotyledon or cotyledons (q. v.), the plumule or future bud, and the radicle or future root. For distinctions of plants founded on the number of their cotyledons a very important character-see Dicotyledons, Monocotyledons, and Acotyledons. B. As adj .: In a rudimentary, crude, or undeveloped state; undeveloped; not in a perfect state. "Four champions fierce, IMG:content-0922.png:[ocr errors] Strive here for mastery, and to battle bring Their embryon atoms." s." Milton : P. L., ii. 898-900. Crabb thus discriminates between embryo and fætus: " Embryo signifies the thing germinated; fætus signifies the thing cherished, both words referring to what is formed in the womb of the mother; but embryo properly implies the first fruit of conception, and the fetus that which has arrived to a maturity of formation. Anatomists tell us that the embryo in the human subject as sumes the character of the fætus about the forty second day after conception. Fortus is applicable only in its proper sense to animals; embryo has a figurative application to plants and fruits when they remain in a confused and imperfect state, and also a moral application to plans, or whatever is roughly conceived in the mind." (Crabb: Eng . Synon.) (1) Fixed embryo : Bot.: A leaf bud. (2) Naked embryo: Veg. Phys.: A spore. embryo-buds, s. pl . Veg. Phys.: Spheroidal solid bodies found in the bark of trees, and capable in favorable circumstances of being transformed into branches. They may be well seen on the beech tree. The name was first given by Dutrochet. IMG:content-0923.png:[blocks in formation] embryo-sac, s. 1. Human & Animal Phys.: [EMBRYO, 1, 2.] 2. Veg. Phys.: A cell which becomes enlarged into a sac in the substance of the upper part of the nucleus of the ovule or rudiment of the seed. In its cavity are developed the germinal vesicles, one (if not more) of which after fertilization gives origin to the embryo. ( Griffith & Henfrey .)