ON THE MECHANISM OF THE EYE, 606 



Fig. 86. Change of figure, which would be the consequence of the action of those 

 muscles upon tlie eye, and upon the adipose substance behind it. 



Fig. 87. Scale of the small optometer. 



Fig. 88. Appearance of four images of a line seen by my eye when its focus is shortest. 



Fig. 89- Outline of the lens, when relaxed ; from a comparison of M. Petit's measures with 

 the phenomena of my own eye, and on the supposition that it is found in a relaxed state 

 after death. 



Fig. 90. Outline of the lens sufficiently changed to produce the shortest focal distance. 



Fig. 91. Apparatus for ascertaining the fooal length of the lens in water. 



Plate 12. Fig. 92. n. 28. Various forms of the image depicted by a cylindrical pencil of 

 rays obliquely refracted by a spherical surface, when received on planes at distances pro- 

 gressively greater. 



Fig. 92. n. 29. Image of a minute lucid object held very near to my eye. 



Fig. 92. n.30. The same appearance when the eye lias been rubbed. 



Fig. 92. n. 31.. .37- Different forms of the image of a lucid point at greater and greater 

 distances ; the most perfect focus being like n. ,'J3, but much smaller. 



Fig. 92. n. 38. Image of a very remote point seen by my right eye. 



Fig. 92. n. 39. Image of a remote point seen by my left eye ; being more obtuse at one 

 end, probably from a less obliquity of the posterior surface of the crystalline lens. 



Fig. 92. n. 40. Combination of two figures similar to the filth variety of n. 28; to 

 imitate n.38. 



Fig. 92. n. 41. Appearance of a distaiil lucid point, when the eye is adapted to a very 

 near object. 



Fig. 92. n. 42, 44. Shadow of parallel wires in the image of a distant point, when the 

 eye is relaxed. 



Fig. 92. n. 43, 45. The same shadows rendered curved by a change in the figure of the 

 crystalline lens. 



Fig. 93. The order of the fibres of the hum^n crystalline. 



Fig. 94. The division of the nerves at the ciiiary zone ; the scleiotica being removed. 

 One of the nerves of the uvea is seen passing forwards and subdividiiig. From the calf. 



Fig. 95. Ramifications from the margin of the crystalline lens. 



Fig. 9(5. The zone of the crystalline faintly seen through the capsule. 



Fig. 97. The zone raised from its situation, with the ramifications passing through- it into 

 the lens. 



Fig. 98. The zone of the crystalline detached. 



Plate 13. Fig. 99. The crenated zone, and the globules regularly arranged on 

 the crystalline of the partridge. 



Fig. 100. The order of the fibres in the lens of birds and fishes. 



Fig. 101. The segments of the capsuleof the crystalline lurneJ back, to show the detached 

 ciliary processes. From the calf. 



