Inquiries respecting the anatomy of the eye / [Arthur Jacob].

  • Arthur Jacob
Date:
1823
Catalogue details

Licence: Public Domain Mark

Credit: Inquiries respecting the anatomy of the eye / [Arthur Jacob]. Source: Wellcome Collection.

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    ciliary processes. The pupil is immediately sur¬ rounded by a well-defined distinct circle, about the twentieth part of an inch in diameter, of a denser structure than the rest of the iris; this is what has long been described as the orbicular muscle or con¬ strictor of the pupil. If the iris be treated as I before mentioned, by maceration and extension, this appearance still preserves its integrity, and re¬ tains its original character (see Fig. 2. PI. IX). From the foregoing observations, I conclude that, if experiment leads to the inference that the iris is a muscular body capable of dilatation and contrac¬ tion, its anatomical structure strengthens the con¬ clusion; and that this muscular power more proba¬ bly resides in this remarkable structure in front, than in the radiating fibres (as they have been called) behind. The arguments which have been advanced in favour of a dilating power in the radi¬ ating striae, apply equally to this fasciculated struc¬ ture of the anterior surface. On the Memhrana Papillaris. The memhrana papillaris is generally supposed to disappear about the seventh month of foetal life. I shall endeavour to show that this occurrence does not take place until about the period of birth, as should, indeed, have been previously supposed. If the eye be examined about the fifth month, the
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