Book excerpt: Excerpt from Medical Jurisprudence, Forensic Medicine and Toxicology, Vol. 3 The acuteness of vision of an eye-witness may have an important bearing upon the credibility of his testimony. It may have an important bearing on those cases of alleged direct or indirect injury to the visual apparatus, in which the simulating plaintiff is actuated by revengeful motives, or by a dishonest desire for pecuniary remuneration for his alleged hurt. It must he taken into consideration likewise in those cases of actual injury, direct or indirect, to the visual apparatus, in which justice would naturally side with the injured party, to the end that the degree of his incapacity may be correctly determined. The visual apparatus comprises the eyeball together with its extrinsic muscles, the optic nerves, the chiasm, the optic tracts, and the centres of visual perception in the brain. Acuteness of vision depends upon the integrity of these structures. The eyeball is really a living camera. Upon its retina is projected an instantaneous and transient photograph of the objects seen. By virtue of the transmission of such impressions upon the retina to the centres of vision in the occipital lobes, by the optic nerves, the chiasm, the optic tracts, and the prolongations of the optic tracts, the retinal image of the object under observation is perceived. If the retinal images be true and if impressions of them be properly transmitted to a normal visual centre, the perceptions of the object will be correct, so far as concerns the visual apparatus. It often happens, however, that the retinal images are not clear and distinct: under certain conditions they do not represent the thing as it is. The reason for this must often he sought in the state of the refraction of the eye. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.