Structure of the Eye. 63 



screen is self-adjusting, with a net-work that no art 

 of man ever equalled. Whether expanding or con- 

 tracting, its opening in the centre always remains a 

 perfect circle, adapted in size to the intensity of 

 light. I low much light shall enter the eye it deter- 

 mines without aid from us. Next there must be 

 connection with the brain, the seat of the being for 

 whom the provision is made. These two coatings 

 pieived upon the back part of the eye, and a 

 thread drawn out from the brain is passed through 

 this opening and spread out within the eye as a 

 delicate sen < n which all impressions are to be 



made. To fill the larger portion of the cavity, th 

 is parked into it a clear jelly, and imbedded in this 

 :i lens, fashioned with a skill that no artist ran equal, 

 to refract the li-ht and throw the image on the per- 

 ceptive screen. In front of this lens is another 

 humor, not like jelly as the other, because in this, 

 that delicate fringe, the iris, is to float, and nothing 

 but a watery fluid will answer its purpose. Here 

 then we have a great variety of materials all brought 

 together, of the exact quality and in the quantity 

 needed, placed in the exact position which they 

 ought to occupy, so perfectly adjusted that the most 

 that man can do is to imitate the eye without ever 

 hoping to equal it. 



Nor is the curious structure of the eye itself all 

 that is worthy of our attention. The instrument 

 when finished must be mounted for use. A cavity 

 is formed in solid bone, with grooves and perfora- 

 tions for all the required machinery. The eye, when 



