Seg, n. [Probably from the root of L. secare to cut.] A castrated bull.
[Prov. Eng. & Scot.] Halliwell.
Se*gar" (?), n. See Cigar.
Seg"gar (?), n. [Prov. E. saggard a seggar, seggard a sort of riding
surtout, contr. fr. safeguard.] A case or holder made of fire clay, in
which fine pottery is inclosed while baking in the kin. [Written also
saggar, sagger, and segger.] Ure.
Segge (?), n. (Zoöl.) The hedge sparrow. [Prov. Eng.] Halliwell.
Seg"ment (?), n. [L. segmentum, fr. secare to cut, cut off: cf. F.
segment. See Saw a cutting instrument.] 1. One of the parts into which
any body naturally separates or is divided; a part divided or cut off;
a section; a portion; as, a segment of an orange; a segment of a
compound or divided leaf.
2. (Geom.) A part cut off from a figure by a line or plane; especially,
that part of a circle contained between a chord and an arc of that
circle, or so much of the circle as is cut off by the chord; as, the
segment acb in the Illustration.
3. (Mach.) (a) A piece in the form of the sector of a circle, or part
of a ring; as, the segment of a sectional fly wheel or flywheel rim.
(b) A segment gear.
4. (Biol.) (a) One of the cells or division formed by segmentation, as
in egg cleavage or in fissiparous cell formation. (b) One of the
divisions, rings, or joints into which many animal bodies are divided;
a somite; a metamere; a somatome.
Segment gear, a piece for receiving or communicating reciprocating
motion from or to a cogwheel, consisting of a sector of a circular
gear, or ring, having cogs on the periphery, or face. -- Segment of a
line, the part of a line contained between two points on it. -- Segment
of a sphere, the part of a sphere cut off by a plane, or included
between two parallel planes. -- Ventral segment. (Acoustics) See Loor,
n., 5.
Seg"ment (?), v. i. (Biol.) To divide or separate into parts in growth;
to undergo segmentation, or cleavage, as in the segmentation of the
ovum.
Seg*men"tal (?), a. 1. Relating to, or being, a segment.
2. (Anat. & Zoöl.) (a) Of or pertaining to the segments of animals; as,
a segmental duct; segmental papillæ. (b) Of 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
segmental ducts. (b) (Zoöl.) The tubular excretory organs, a pair of
which often occur in each of several segments in annelids. They serve
as renal organs, and often, also, as oviducts and sperm ducts. See
Illust. under Sipunculacea. -- Segmental tubes (Anat.), the tubes which
primarily open into the segmental duct, some of which become the
urinary tubules of the adult.
Seg`men*ta"tion (?), n. The act or process of dividing into segments;
specifically (Biol.), a self-division into segments as a result of
growth; cell cleavage; cell multiplication; endogenous cell formation.
Segmentation cavity (Biol.), the cavity formed by the arrangement of
the cells in segmentation or cleavage of the ovum; the cavity of the
blastosphere. In the gastrula stage, the segmentation cavity in which
the mesoblast is formed lies between the entoblast and ectoblast. See
Illust. of Invagination. -- Segmentation nucleus (Biol.), the body
formed by fusion of the male and female pronucleus in an impregnated
ovum. See the Note under Pronucleus. -- 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 again divides into two, and so on, thus giving rise to a mass of
cells (mulberry mass, or morula), all equal and similar, from the
growth and development of which the future animal is to be formed. This
constitutes regular segmentation. Quite frequently, however, the
equality and regularity of cleavage is interfered with by the presence
of food yolk, from which results unequal segmentation. See Holoblastic,
Meroblastic, Alecithal, Centrolecithal, Ectolecithal, and Ovum. --
Segmentation sphere (Biol.), the blastosphere, or morula. See Morula.
Seg"ment*ed (?), a. Divided into segments or joints; articulated.
{ Seg"ni*tude (?), Seg"ni*ty (?) }, n. [L. segnitas, fr. segnis slow,
sluggish.] Sluggishness; dullness; inactivity. [Obs.]
||Se"gno (?), n. [It. See Sign.] (Mus.) A sign. See Al segno, and Dal
||segno.
Se"go (?), n. (Bot.) A liliaceous plant (Calochortus Nuttallii) of
Western North America, and its edible bulb; -- so called by the Ute
Indians and the Mormons.
Seg"re*gate (?), a. [L. segregatus, p. p. of segregare to separate;
pref. se- aside + grex, gregis, a flock or herd. See Gregarious.] 1.
Separate; select.