Hand-book of physiology (1892) (14578769188)

Identifier: handbookofphysio00bake (find matches)

Title: Hand-book of physiology

Year: 1892 (1890s)

Authors: Baker, W. Morrant, (William Morrant), 1839-1896 Harris, Vincent Dormer Kirkes, William Senhouse, 1823-1864. Hand-book of physiology. 13th ed

Subjects: Physiology Human physiology

Publisher: London : John Murray

Contributing Library: Francis A. Countway Library of Medicine

Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

Text Appearing Before Image:

above ; but far more to the fact that everysuch ray is reflected straight to the source of light (e.g., candle),and cannot, therefore, be seen by the unaided eye without intercept-ing the incident light from the candle, as well as the reflected raysfrom the retina. This difficulty is surmounted by the use of theophthalmoscope. The ophthalmoscope, brought into use by Helmholtz, consists in itssimplest form of a, a slightly concave mirror of metal or silvered glass 746 THE SENSES. (CH. XVII. perforated in the centre, and fixed into a handle ; and b, a biconvex lensof about 2J-3 inches focal length. Two methods of examining the eyewith this instrument are in common use—the direct and the indirect: bothmethods of investigation should be employed. A normal eye should beexamined ; a drop of a solution of atropia (two grains to the ounce) or ofhomatropia hydrobromate, should be instilled about twenty minutes beforethe examination is commenced ; the ciliary muscle is thereby paralysed, the

Text Appearing After Image:

Fig. 429.—Diagram to illustrate the action of the Ophthalmoscope, when a plane concaveglass is used. c. observers eye. The light reflected from any point, d, on retina of a,would naturally be focussed at e; if the lens b is used it would be focussed at i, inother words, at back of c. The image would be enlarged, as though of g, and would beinverted. (After McGregor Robertson.) power of accommodation is abolished, and the pupil is dilated. This willmaterially facilitate the examination ; but it is quite possible to observe allthe details to be presently described without the use of this drug. Theroom being now darkened, the observer seats himself in front of the personwhose eye he is about to examine, placing himself upon a somewhat higherlevel. A brilliant and steady light is placed close to the left ear of thepatient. The atropia having been put into the right eye only of the patient,this eye is examined. Taking the mirror in his right hand, and lookingthrough the central hole, the

hand book of physiology 1892 book illustrations medicine medical illustrations medical history physiology images from internet archive

1892

Open Knowledge Commons and Harvard Medical School

http://commons.wikimedia.org/

public domain