224 



SENSE OF SIGHT. 



Fig. 102. 



Fig. 103. 



A representation of some of the Nerves of the 

 Orbit, especially to show the Lenticular Ganglion. 

 (Arnold.) 



1. Ganglion of the fifth. 2. Ophthalmic nerve. 3. 

 Upper maxillary. 4. Lower maxillary. 5. Nasal 

 branch, giving the long root to the lenticular ganglion. 

 6. Third nerve. 7. Inferior oblique branch of the third 

 connected with the ganglion by the short root. 8. Optic 

 nerve. 9. Sixth nerve. 10. Sympathetic on the caro 

 tid artery. 



Fig. 104. 



Segment of the Anterior Face of the 

 Iris with its Vessels injected. Magnified 

 25 diameters. 



1, 1. Portion of the pupillary circumfer- 

 ence of the iris. 2,2. Part of its greater cir- 

 cumference surrounded by a branch of the 

 long ciliary artery. 3. Part of the lesser circle 

 of the iris. 4, 4. Part of its greater circle. 

 5, 5. Three arteries which are larger than the 

 others, and coming from the greater circle are 

 lost in the iris. 6. Smaller arteries arising 

 from these. 7. Branches of the larger arte- 

 ries, which are lost in the smaller circle of 

 the iris. An outline of the natural size of 

 this piece is seen on the left side of the figure 

 between 3 and 7. 



Berzelius, 1 too, affirms, that 

 the iris has all the chemical 

 characters of muscle. 



The iris is the coloured part 

 of the eye seen through the 

 transparent cornea; and, ac- 

 cording to the particular co- 

 lours reflected from it, the eye 

 is said to be blue, gray, hazel, 

 &c. In its centre is an open- 

 ing, called pupil, through 

 which alone the rays of light 

 can reach the lens. This open- 

 ing can be enlarged or con- 



An enlarged View of the Arteries of the Iris. (From tracted by the Contraction Or 



dilatation of the iris; and in 



a. Optic nerve, b. Sclerotic, c. Ciliary ligament, d. Iris. - . . . -.-, 



1. Posterior ciliary arteries perforating the sclerotic. thlS rCSpCCt it IS perpetually 



2. Long (external) ciliary artery. 3. Anterior (short) varv ; T1o . PPnr (li n o- to 

 ciliary arteries. (The figure is larger than natural.) varying, according IO 



1 View of the Progress of Animal Chemistry, p. 86, Lond., 1843. 



