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pale green mineral occurring in crystalline aggregates having a botryoidal or mammillary structure, and rarely in distinct crystals. It is a hydrous silicate of alumina and lime.

corals. Proliferous cyst (Med.), a cyst that produces highly- organized or even vascular structures. Paget. -- Pro*lif"er*ous*ly, adv.

l properties. Chemical properties are identical when there is identity of composition and structure, and change according as the composition changes. 3. Organoleptic properties, or those forming a class which can not be included in either of the other two divisions. They manifest themselves in the contact of substances…

Relative position of the front of a building or other structure; face; relative aspect. And their prospect was toward the south. Ezek. xl. 44.

ually of a gray color, the pores of which are capillary and parallel, giving it a fibrous structure. It is supposed to be produced by the disengagement of watery vapor without liquid or plastic lava. It is much used, esp. in the form of powder, for smoothing and polishing. Called also pumice stone.

Resembling, or having the structure of, pumice.

indicating purpose or design. "Purposive characters." Bastian. Purposive modification of structure in a bone. Owen. It is impossible that the frog should perform actions morepurposive than these. Huxley.

iangular, square, or polygonal base, and terminating in a point at the top; especially, a structure or edifice of this shape.

ing parts or markings diverging, like radii, from a common center or axis; as, a radiated structure; a radiated group of crystals.

The light, fencelike structures of wood or metal at the break of the deck, and elsewhere where such protection is needed. Rail fence. See under Fence. -- Rail guard. (a) A device attached to the front of a locomotive on each side for clearing the rail obstructions. (b) A guard rail. See under Guard. -- Rail joint (Ra…

d adjusted to be tracks for the wheels of vehicles, and suitably supported on a bed or substructure.

cumulation of materials or constituent parts; to build up; to erect; as, to raise a lofty structure, a wall, a heap of stones. I will raise forts against thee. Isa. xxxix. 3.

Expressing the type, structure, relations, and reactions of a compound; graphic; -- said of formulæ. See under Formula. Rational horizon. (Astron.) See Horizon, 2 (b). -- Rational quantity (Alg. ), one that can be expressed without the use of a radical sign, or in extract parts of unity; -- opposed to irrational or ra…

Any organ of an animal having a structure adapted to produce a ratting sound.

oducing photographic and fluorescent effects by which means pictures showing the internal structure of opaque objects are made, called radiographs, or sciagraphs. So called from the discoverer, W. C. Röntgen. -- X ray, the Röntgen ray; -- so called by its discoverer because of its enigmatical character, x being an alg…

Similar in general appearance, structure, and habits, but living in different regions; -- said of certain species and varieties.

Resembling network; having the form or appearance of a net; netted; as, a reticulated structure.

Backward development; a passing from a higher to a lower state of organization or structure, as when an animal, approaching maturity, becomes less highly organized than would be expected from its earlier stages or known relationship. Called also retrograde development, and regressive metamorphism.

A minute smooth rodlike or fusiform structure found in the tissues of many Turbellaria.

A minute calcareous rodlike structure found both at the surface and the bottom of the ocean; -- supposed by some to be a calcareous alga.