pupil

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pupil:

see eyeeye,
organ of vision and light perception. In humans the eye is of the camera type, with an iris diaphragm and variable focusing, or accommodation. Other types of eye are the simple eye, found in many invertebrates, and the compound eye, found in insects and many other
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.

Pupil

 

the opening in the iris through which light rays enter the eye.

The dimensions of the pupil change according to the amount of light present: the pupil dilates in darkness, under emotional excitement and painful sensations, or with the injection of atropine or adrenalin into the body; it contracts in bright light. Change in the dimensions of the pupil is regulated by fibers of the autonomic nervous system and is accomplished by means of two smooth muscles located in the iris—the sphincter, which contracts the pupil, and the dilator, which expands it. In higher vertebrates, changes in the dimensions of the pupil are produced reflexively by the effect of light on the retina of the eye; in lower vertebrates, these changes are produced by the direct action of light on contrac-tile formations in the pupil. The pupil is usually round or slitlike; in some fish (for example, in a number of sharks, rays, and flounder) and mammals (for example, in sperm whales and dolphins) a projection of the iris, suspended from the superior edge of the pupil, can cover the pupil completely in the presence of intense illumination. In man the pupil is round; its diameter may change from 1.1 mm to 8 mm. Changes in the shape, dimensions, and speed of reaction of the pupil (so-called pupillary reflexes) are of diagnostic significance in eye diseases.

O. G. STROEVA

pupil

[′pyü·pəl]
(anatomy)
The contractile opening in the iris of the vertebrate eye.

pupil

1
1. a student who is taught by a teacher, esp a young student
2. Civil and Scots law a boy under 14 or a girl under 12 who is in the care of a guardian

pupil

2
the dark circular aperture at the centre of the iris of the eye, through which light enters
References in classic literature ?
I entered, and found two young ladies and two young gentlemen--my future pupils, I supposed.
I descended to the schoolroom with no remarkable eagerness to join my pupils, though not without some feeling of curiosity respecting what a further acquaintance would reveal.
The accidents of conversation; the simple habits which regulated even such a little thing as the position of our places at table; the play of Miss Halcombe's ever-ready raillery, always directed against my anxiety as teacher, while it sparkled over her enthusiasm as pupil; the harmless expression of poor Mrs.
Do have something more to say about your pupil's letter?" She noiselessly drew her chair forward, as she said these words, a few inches beyond the line of the visitor's chair.
The language you have allowed yourself to use in my absence is the same language which your pupil was foolish enough to employ when she wrote for the second time to my late master.
You may tell Miss Smith that I forgot to make a memorandum of the darning needles, but she shall have some papers sent in next week; and she is not, on any account, to give out more than one at a time to each pupil: if they have more, they are apt to be careless and lose them.
Pelet's establishment, the combined insubordination of the pupils had effected the dismissal of more than one English master.
The girls of the aristocratic group of pupils belonged to the most devoted royalist families in Paris.
Miss Peecher and Miss Peecher's pupils were not much encouraged in the unscholastic art of needlework, by Government.
She was the best pupil I ever had--and I remember she lived in Yorkshire." He was so weary of the idle curiosity--as it appeared to him--which persisted in asking trifling questions, that he left his seat, and crossed the room.
Although schoolmistresses' letters are to be trusted no more nor less than churchyard epitaphs; yet, as it sometimes happens that a person departs this life who is really deserving of all the praises the stone cutter carves over his bones; who IS a good Christian, a good parent, child, wife, or husband; who actually DOES leave a disconsolate family to mourn his loss; so in academies of the male and female sex it occurs every now and then that the pupil is fully worthy of the praises bestowed by the disinterested instructor.
"Prince Vasili finds you to his taste as a daughter-in-law and makes a proposal to you on his pupil's behalf.