Pl. -acula. [L. spīrāculum, f. spīrāre to breathe.]

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  1.  = SPIRACLE1 2 b.

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a. 1668.  Lassels, Voy. Italy (1670), II. 295. There are divers spiracula, or Vents round about it, out of which the thick smoke presseth furiously.

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a. 1705.  Ray, Disc., II. (1713), 13. The enclosed Fire was not of Force sufficient to make its way out, or found not Spiracula to vent itself.

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1789.  E. Darwin, Bot. Gard., I. (1791), Notes 12. The volcanos themselves appear to be spiracula or chimneys belonging to great central fires.

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1820.  T. S. Hughes, Trav. Sicily, I. iv. 115. It contains two principal spiracula, or vents, from whence … huge stones and rocks are precipitated.

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  2.  = SPIRACLE1 2.

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a. 1734.  North, Examen, II. v. § 74 (1740), 360. Like a Chymist’s Fire,… upon opening the Spiracula of the Furnace … the Flame broke out.

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  3.  Zool. = SPIRACLE1 3 c.

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1768.  G. White, Selborne, xiv. If some curious gentleman would procure the head of a fallow deer … he would find it furnished with two spiracula, or breathing places, besides the nostrils.

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1797.  Encycl. Brit. (ed. 3), VI. 676/2. All insects … respire through pores … which are termed spiracula.

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1816.  Kirby & Sp., Entomol. (1818), II. 425. The remarkably large spiracula in glow-worms.

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1878.  F. J. Bell, Gegenbaur’s Comp. Anat., 396. Peripheral nerves pass out from the anterior ganglion…. Others pass backwards to the spiracula.

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