( 250 ) 



" of thcfe is made up of a fingle fibre, or fine thread, running this 

 " way and that, in Icvcral courfcs, and meeting in as many centers, 

 " and yet not interfering with, or eroding, each other. 



'• The yellow colour wherewith the cryltallinc is more and Jiiore 

 " tinged as we advance in years, mufl make all objefts appear more 

 " and more tinged with that colour : nor does our being infenfible of 

 *' any change in the colour of objecHs, prove to us that their colour 

 " continues the fame ; for in order that we fhould be fenfible of this 

 " change, the tincture murt not only be confiderablc, but it muft hap- 

 " pen on a fudden. In the cataract it is opake ; the feat of this dii- 

 " order is in the cryftalline lens. 



*' Vitreous Humour. 



" The vitreous is the third humour of the eye; it receives its name 

 " from its appearance, ^^hic]l is like that of melted glafs. It is nei- 

 " ther fo hard as the cryfiaUine, nor fo liquid as the aqueous humour; 

 " it fills the greateft part of the eye, extending from the infertion of 

 " the optic nerve to the cryfiallinc humour. It fupports the retina, 

 " and keeps it at a proper diilance for receiving and forming dlf- 

 " tin(5l images of objects. 



" The vitreous humour is contained in a very thin pellucid membrane, 

 "and concave at its fore part, to receive the cryfialline; at this 

 " place its membrane divides into t^^ o, the one covering the cavity 

 " in which the cryRalline lies, the other pafTuig above, and covering 

 " the fore part of the cryfialline, thus forming a kind of flieath for 

 " the cryftalline. The fabric of the vitreous humour is cellular, 

 " the fubfiance oi" it being divided by a very fine tranl'parcnt mem- 

 " brane into cellules, or little membraneous coinpartmcnts, con- 

 " taining a very tranfparent liquor. 



" Ligamcntum Ciliare. 

 .»' There is flill one j-»art to be dcfcribed, w^iiich, though very 



