THE EYE. 31 



glass will represent that glass-like covering of the 

 QjQ which we call the ' cornea.' I fear we shall 

 have to draw rather largely on our imagination to 

 carry oar illustration further. Let us see. Sup- 

 pose you have a pair of spectacles with round 

 glasses instead of oval ones, and you could remove 

 one of these glasses, and (without rupturing our 

 artificial ' iris ') you could thrust it through the 

 ' pupil ' and place it immediately at the back of the 

 ' iris,' this glass lens would then represent the 

 ' lens ' of the eye. Just a little further stretch of 

 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, silver 

 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, D, and we find the 

 diagram of a real eye in section. Now, you will 

 see the parts marked in the diagram as we have 

 described them. First : the greater part of the 

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

 ivJdte tunic of the eye called the ivhite of the eye, 

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

 watch-glass) is the ' cornea ' f Fig. 5, I) c,) then 

 behind this we have the iris D I. Then behind 



