LESSONS IN HORSE JUDGING. 39 



the imagination, then no more. When you took 

 the lens out of the spectacles (in imagination of 

 course) you found it surrounded by the iron, sil- 

 ver or gold rim which held it. You have placed 

 the lens in the orange as described, and now in 

 place of a metal rim around it, suppose we have 

 a sheet-like muscle encircling the lens, and that 

 the outer edge, all round, of this sheet-like muscle, 

 is fixed to the interior of the orange peel a little 

 further back than the lens. 



We now look at Fig. 5, 7), and we find the dia- 

 gram of a real eye in section. Now, you will see 

 the parts marked in the diagram as we have de- 

 scribed them. First: the greater part of the 

 outer coat (five-sixths we said) is formed by the 

 ivliite tunic of the eye called the white of the eye 

 (Fig. 5, D 1). The remainder of the circle (our 

 watch-glass) is the ^ cornea ' (Fig. 6, D c), then 

 behind this we have the iris D I. Then behind 

 this again the lens D. I. with its muscle, the cil- 

 iary muscle {D 2). 



Let us describe the remainder of the eye by the 

 aid of the lower diagram we are now looking at. 

 That very large space marked V H is filled by a 

 transparent jelly-like substance called the vitreous 

 humor. Then you see the nerve of sight as it 

 comes from the brain {D, o n) piercing the back 

 of the white outer tunic like the end of a lead- 

 pencil, and when it has gained the inner part of 

 the tunic it spreads out like a sheet of tissue 

 paper, and lines the back of the white tunic in- 

 side and is known as the ^ retina ' {DR). In this 

 thin filmy sheet or ^retina,' close to the optic 



