| 释义 |
pinnule|ˈpɪnjuːl|
Also (in sense 1) 6–8 pinule; (in senses 2 and 3) in Lat. form pinnula (pl. -æ).
[ad. L. pinnula, dim. of pinna plume, wing: see pinna2.]
1. Each of the two sights (consisting of a small square metal plate, pierced with holes, and turning on a hinge) at the ends of the ‘alidade’ or index of an astrolabe, quadrant, or similar instrument.
1594Blundevil Exerc. vi. Introd. (1636) 608 Which Diopter is made with two Pinules or square Tablets. 1656W. D. tr. Comenius' Gate Lat. Unl. §528 Out of two stations by the pinnules of the radius..they collect the quantity of the lines of a greater triangle, which is made between the two stations and the thing seen. 1773Gentl. Mag. XLIII. 171 He has joined pinules to his barometer, which by this means furnishes him with an instrument for levelling. 1834Nat. Philos. III. Hist. Astron. xiii. 67/1 (Usef. Knowl. Soc.) A radius, moveable on the centre of the circle, carried the pinnules, and traced out with its extremity..the arc it was wished to measure. 1879Newcomb & Holden Astron. 59.
2. Bot. Each of the secondary or ultimate divisions of a pinnate leaf; a subdivision of a pinna (branchlet, leaflet, or lobe): esp. in ferns.
1776–96Withering Brit. Plants (ed. 3) III. 873 Distinct from J. trilobata, the pinnules of which are eared and the leafits smaller. 1857Henfrey Bot. §95 In the Ferns..the primary divisions of the leaf are called pinnæ, the secondary pinnules, and the tertiary lobes or segments. 1877Academy 3 Nov. 434/1 A long central rachis, carrying sub-sessile pinnules.
3. Zool. A part or organ resembling a small wing or fin, or a barb of a feather; spec.
a. A small fin-like appendage, or short detached fin-ray, in certain fishes, as the mackerel.
b. Each of the lateral branches of the arms in crinoids.
1748Hartley Observ. Man i. i. 89 The rhomboidal Pinnulae in the abdominal Muscles of a living Frog, when under Contraction. 1752J. Hill Hist. Anim. 244 The Scomber, with five pinnules at the extremity of the back. 1877W. Thomson Voy. Challenger II. ii. 97 The pinnules arising from either side of the arm alternately.
Hence ˈpinnular a., of or pertaining to a pinnule; ˈpinnulate, ˈpinnulated adjs., having pinnules; ˈpinnulet [-et], a small or subordinate pinnule; ‖ ˈpinnulus, a form of 6-rayed spicule in sponges.
1828–32Webster, A Pinnulate leaf is one in which each pinna is subdivided. 1877Huxley Anat. Inv. Anim. ix. 582 Pedicels..continued throughout the brachial and pinnular grooves. 1881Gard. Chron. XVI. 685 The pinnæ, pinnules, and alternate pinnulets are all stalked. 1887Sollas in Encycl. Brit. XXII. 417/1 The suppression of the proximal ray and the development of spines projecting forwards on the distal ray produce the pinnulus. 1890Cent. Dict., Pinnulated. |