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the opposite belief were shown to furnish no substantial support of 

 the current opinion. Thus, the eyes of albino animals were found 

 to exercise vision perfectly, although destitute of pigmentum ni' 

 grum ; and the presence of the tapetum lucidum, which acts like 

 a concave metallic reflector in the eyes of many creatures, was 

 shown to furnish no obstacle to sight, which, on the other hand, 

 it rendered more acute when light was feeble. The supposed cross 

 reflection of light within the eye was also shown to be a phenomenon 

 which could rarely occur so as to disturb vision, since the majority 

 of the reflected rays would simply retrace the course which they 

 took on entering the eye, and pass out through the pupil as they 

 passed in through it ; and the few which diverged so much as to 

 fall on the back of the iris, the ciliary processes and the anterior 

 lateral surface of the choroid, would be caught upon the darkest and 

 least reflecting portion of the interior of the eye, and undergo in 

 greater part absorption, whilst such as were not thus stopped, and 

 those which underwent lateral reflection from the bottom of the eye, 

 would be irregularly dispersed over the entire retina, and only lessen 

 its general sensitiveness without repeating the images of objects on 

 single points of its surface. 



The author finally urged that the reflection of light from the 

 bottom of the eye served important ends, especially in the lower 

 animals. Those ends he held to be ; — 



1. The return from the choroid of light through the retina, so as 

 to double the impression on the latter. 



2. The reflection of light on external objects, which was best 

 seen in creatures whose eyes are provided with tapeta lucida, and 

 acted alike as an assistance to them in finding their food, and in the 

 case of carnivorous nocturnal and marine animals, to their prey in 

 escaping from them. 



In the human subject, it was contended that, in very faint light, 

 reflection from the bottom of the eye would assist vision, and that 

 the known delicacy of visual perception, which characterised those 

 who had been long imprisoned in dark chambers or dungeons, 

 afforded an example of such assistance. The author also insisted 

 on the fact, that, as the reflected light is always coloured, so as in 

 the human eye to be bright red, yellowish-red, or brownish-red, and 

 in different eyes to a different degree ; and as we add from our eyes 

 coloured light to every object we gaze at, no two persons see the same 

 colour alike, or will exactly agree in matching tints. The existence 



