POL 



POL 



9. Poly-galacers. The Milkwort tribe 

 of dicotyledonous plants. Shrubs or her- 

 baceous plants with leaves generally alter- 

 nate; flowers polypetalous, unsymme- 

 trical ; stamens hypogynous ; ovary 2- 

 celled ; fruit dehiscent. 



10. PoZe/-5^amia (7a/jio?, nuptials). The 

 name of the twenty-third class in the 

 Linnaean system of plants, comprising 

 those which bear hermaphrodite and uni- 

 sexual flowers on the same individual ; 

 or hermaphrodites on one individual, 

 males on a second, and females on a 

 third. 



11. Poly-gastrica {yaa-Trjp, a stomach). 

 A class of Radiated animals, having nu- 

 merous stomachs or coeca communicating 

 with an internal alimentary cavity, with- 

 out perceptible nerves or muscles, but 

 moving by means of external vibratile 

 cilia. 



12. Poly-gon (70) vm, an angle). A 

 rectilinear figure, bounded by more than 

 four sides. Polygons are called penta 

 gons, hexagons, heptagons, &c., accord- 

 ing as they are bounded by five, six, 

 seven, or more sides. A line joining the 

 vertices of any two angles which are not 

 adjacent is called a diagonal of the poly- 

 gon. 



13. Poly-gon of Forces. A theorem in 

 mechanics, which may be thus stated : — 

 If any number of forces act upon a point, 

 and a polygon be taken, one of the sides 

 of which is formed by the line represent- 

 ing one of the forces, and the following 

 sides in succession by lines representing 

 the other forces in magnitude, and 

 parallel to their directions, then the line 

 which completes the polygon will repre- 

 sent the resultant of all the forces. 



14. Poly-gonal (^wi/t'a, an angle). A 

 term applied, in arithmetic, to certain 

 numbers possessing this property, that 

 the same number of points may be 

 arranged in the form of that polygonal 

 figure to which they belong. SeeFigurate 

 Number, and Number. 



15. Poly-gonaceee. The Buck-wheat 

 tribe of dicotyledonous plants, herbace- 

 ous plants with leaves alternate ; flowers 

 occasionally unisexual ; stamens definite ; 

 ovary superior; seed with farinaceous 

 albumen. 



16. Poly-gynia {"^vvt], a woman). The 

 designation of those orders of plants in 

 the Linnaean system, in which there is 

 an indefinite number of stamens. 



17. Poly-halite (aX?, salt). A chemical 

 compound of several sulphates, formerly 

 mistaken for anhydrous sulphate of lime ; 



267 



compact and fibrous, from the salt forma- 

 tion in Bavaria and Austria. 



18. Poly-hedron (eSpa, a seat or side). 

 A geometrical solid bounded by several 

 faces or planes. In every solid poly- 

 hedron, the number of faces and corners 

 exceeds the number of edges by two. 



19. Poly-meric {fxepo^, a part). A term 

 applied in chemistry to those bodies 

 which contain the same relative, but not 

 the same absolute number of atoms of 

 the same elements, and whose atomic 

 weights are consequently unlike. Several 

 carburets of hydrogen afford examples of 

 polymerism. See Isomerism. 



20. Poly-mignite. Titaniate of iron ; 

 a new mineral found sometimes in the 

 zircon-syenite of Fredrickswarn in Nor- 

 way. 



21. Poly-nomial. A barbarous word, 

 sometimes employed in algebra for mul- 

 tinomial, and denoting a quantity of 

 many terms, as the expression 



a -h 2 6 -I- 3 c -t- wrf, &c. 



22. Poly-optron {oirrpov, a looking- 

 glass). A glass for multiplying objects. 

 It consists of a lens one side of which is 

 plane, but the other presents several 

 spherical concavities, each of which 

 becomes a plano-concave lens, and dimi- 

 nishes the object viewed. 



23. Poly-petalous (TreraXov, a flower- 

 leaf). A designation of that kind of 

 corolla, in which the petals are separate 

 from one another, as distinguished from 

 the monopetalous or gamopetalous co- 

 rolla, in which the petals cohere. 



24. Poly-phore {(pepoa, to bear). The 

 name given by Richard to the succulent 

 and dilated receptacle of such plants as 

 the strawberry and the raspberry. More 

 commonly, such a receptacle is suffi- 

 ciently described by the adjective fleshy. 



25. Poly-piaria. Corals. A numerous 

 class of invertebrated animals, belonging 

 to the great division of the Radiata. 



26. Poly-piphera. A class of the Ra- 

 diata, consisting of soft, aquatic animals 

 of a plant-like form, which develope small 

 tubular digestive sacs called polypi, the 

 margins of which are furnished with sen- 

 sitive tentacula, and the sides of the 

 latter with vibratile cilia. 



27. Poly-podiacecB. One of the prin- 

 cipal divisions of the natural order of 

 Ferns, constituting the highest form of 

 acrogenous plants, and exhibiting the 

 nearest approach to the Cycadaceous 

 Gymnosperms. 



28. Poly pus {novi, rroio?, a foot). Un- 

 der the common name Polypi have been 



N2 



