Guide to the practical study of histology : for medical students / by D. Noël Paton, M.D., F.R.C.P.Ed., Professor of Physiology, University of Glasgow, and G. Herbert Clark, M.B., D.P.H., Muirhead Demonstrator of Physiology, University of Glasgow.

Diarmid Noel Paton

Date:: 1908

Credit: Guide to the practical study of histology : for medical students / by D. Noël Paton, M.D., F.R.C.P.Ed., Professor of Physiology, University of Glasgow, and G. Herbert Clark, M.B., D.P.H., Muirhead Demonstrator of Physiology, University of Glasgow. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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$Refracting Surfaces of the Eye. Note the formation of a reflected image from each of the two refracting surfaces of a bi-convex lens. Study- how the size of the image varies with the curvature of the lens, the position of the image from each surface of the lens and the direction in which it moves when the object is moved. Sanson's Images.—In a dark room hold a candle to the outer side of the eye of a fellow student, and notice that three reflected images are to be seen—one large, clear, distinct, erect image from the anterior surface of the cornea, one small distinct inverted image from the posterior surface of the lens and one much less distinct erect image, larger than the first and apparently lying almost behind it and seen best from the side away from the lio-ht, from the anterior surface of the lens. From the size of these images draw conclusions as to the relative curvatures of the different surfaces. Why is no image formed from posterior surface of cornea ? From the results of these observations, make a diagram of the Physiological Lens of the Eye. Can Near and Far Objects be seen at the same time ? Close one eye and fix the other on the far corner of the room, and then hold up a pencil close to the eye and see if at the same time both objects can be distinctly seen. When the eye is directed to the pencil note any change in the pupil. Scheiner's Experiment.—Make two holes in a horizontal line in a sheet of paper so near that they both fall within the diameter of the pupil. Now stand at about two or three yards from a wall on which a small vertical line is drawn and look at it through the holes. While keeping the eye fixed on the line bring a needle vertically in front of the holes at about six inches from the eye, and note the$