THE EYE. 339 



while the whole is held together by the firm connective- tissue 

 network which extends throughout the entire choroid. 



The lamina clwrio-capillaris (cc) consists of a network of 

 line vessels interspersed with pigment, and extends over the 

 whole inner portion of the choroid. 



The vitreous layer () is very closely connected with the 

 lamina chorio-capillaris ; though it appears homogeneous, 

 fibres may be detected in it after long maceration in a ten per 

 cent, solution of common salt. Where this layer covers the cil- 

 ia^ processes the surface is no longer smooth, but has fine, 

 elevated ridges upon it ; here the membrane also is thicker, 

 and is more easily affected by reagents. 



The dense lamina of hexagonal pigment-cells between the 

 choroid and retina has sometimes been classed with the former, 

 although it belongs more properly to the retina. 



The long and short posterior, and the anterior ciliary arte- 

 ries, furnish the numerous blood-vessels which constitute the 

 great mass of the choroid. 



The short posterior ciliary arteries, four to six in number, 

 give off some twenty branches which penetrate the sclera, 

 pursuing a straight course near where the optic nerve enters ; 

 then, continuing their course in a tortuous manner, they divide 

 into fine networks which supply the greater part of the lamina 

 chorio-capillaris. About the entrance of the optic nerve they 

 also form a network of fine vessels, and even send occasional 

 branches to anastomose with vessels from the sheath and cen- 

 tre of the optic nerve. 



The two long ciliary arteries penetrate the sclera in a very 

 oblique course, a little anteriorly to those last mentioned, and 

 in the horizontal meridian ; they pass forward in the outer 

 lamina of the choroid without branching until they reach the 

 ciliary muscle ; here they divide, and penetrating the muscle, 

 form near the periphery of the iris a circle (circulus arteriosus 

 iridis major) by uniting with the artery of the opposite side. 



The anterior ciliary arteries, eight to ten in number, arising 

 from muscular branches of the ophthalmic artery, penetrate 

 the sclera near the insertion of the recti tendons ; they also 

 unite with the circle just described, which forms the principal 

 distributing point for the vessels of the iris and ciliary body. 

 From this circle also are sent back a few small branches to unite 

 with the choroidal capillaries, and there is formed the sole con- 



