446 



CHAMBERS OF THE AQUEOUS HUMOR. 



The aqueous humor is quickly renewed after it has escaped 

 in consequence of wounds or operations, and blood, accident- 

 ally effused into this cavity, is often absorbed.* 



This fluid preserves the convexity of the cornea, and admits 

 the free motions of the iris ; allowing, at the same time, a 

 ready passage to the rays of light. 



Fig. 200.f — The annexed enlarged cut from Soem- 



mering shows accurately the comparative 

 size of the two chambers of the aqueous 

 humor, and how the posterior is formed 

 by the iris in front, the capsule of the lens 

 behind, and the ciliary processes with a 

 small portion of the hyaloid tunic between 

 these processes and the margin of the cap- 

 sule, upon the side. The anterior cham- 

 ber is that formed between the iris and the 

 posterior face of the cornea, 

 — Petit has calculated, that the whole 

 amount of the aqueous humor, does not weigh more than four 

 or five grains, and that the space between the iris and the cap- 

 sule of the lens is less than a quarter or half a line ; while 

 Winslow insisted, that the iris and capsule were in contact in 

 youth and middle life, when the pupil was contracted. 



Certain it is that adhesion takes place readily between them, 



and that the posterior chamber is so narrow, that no surgeon can 

 with any certainty introduce an instrument into it, without the 

 risk of wounding the vascular ciliary processes, or the iris. 



The following are the dimensions and admeasurements 



made by Petit and Young, of the different parts of the globe of 

 the eye. 



Cloquet says, that he has traced it in the posterior chamber of the eye. From 

 this account it appears that there is one capsule, in early foetal life, for the 

 anterior chamber, and another for the posterior chamber, and that the Mem- 

 brana Pupillaris is formed by these capsules being stretched across the pupil, 

 back to back. — h. 



* The aqueous humor, according to Mr. Hunter, can be coagulated with 

 Goulard's Extract.— h. 



f Memoirs of French Academy for 1721. 



