quadrivalentadj.n.

1865 A. W. Hofmann in Chem. News 13 Oct. 176/1 The nitrogen and carbon atoms, respectively trivalent and quadrivalent, are provided with three and four arms, indicating the three and four combining units respectively distinguishing these atoms.

1869 Eng. Mech. 12 Nov. 198/3 The elements are classified as..tetratomic or quadrivalent, having four attractions.

1880 E. Cleminshaw tr. C. A. Wurtz Atomic Theory 283 Carbon is quadrivalent and oxygen bivalent.

1922 A. D. Udden tr. N. Bohr Theory of Spectra iii. iii. 109 While an element like titanium in the fourth period already shows a marked tendency to occur with various valencies, on the other hand an element like zirconium is still quadri-valent like carbon in the second period and silicon in the third.

1978 Sci. Amer. Feb. 58/2 Cerium, alone among the trivalent rare earths, can be oxidized to the relatively insoluble quadrivalent state.

1993 Jrnl. Biol. Chem. 268 11976 The aggregation and triphosphorylation phenomena were not catalyzed by divalent or quadrivalent cations, but similar effects were observed with some other trivalent cations.

1898 Zool. Jahrbücher: Anat. 12 44 Frequently also in the loose spirem are found quadrivalent chromosomes with a constriction about the middle.

1929 Jrnl. Genetics 21 18 The hyacinths offered an opportunity for the comparative study in the same cell of the structure and behaviour of bivalent, trivalent and quadrivalent chromosomes of distinct types.

1992 Res. Vet. Sci. 52 367 Meiotic studies showed a quadrivalent configuration at diakinesis.

1896 Proc. Royal Soc. 60 145 If we calculate these constants for the square root of the atomic weight..we shall obtain for the means—univalents..1·30..quadrivalents..2·12.

1923 Proc. National Acad. Sci. U.S.A. 9 109 In one quarter and more of the pollen-mother-cells this regular distribution does not occur with regard to all of the 12 quadrivalents.

1952 New Biol. 13 35 Sometimes during the nuclear divisions, four chromosomes similar to each other all ‘pair’ together, forming a quadrivalent, instead of the usual two pairs of bivalents.

1975 Nature 17 Apr. 595/2 A sister plant which was a monosomic (2n = 41)..formed some trivalents, quadrivalents,..pentavalents and hexavalents, in addition to bivalents.

1989 Jrnl. Heredity 80 26/1 Accession 3747 had, in addition to quadrivalents, a number of higher multivalents.