THE EMBRYOLOGY OF THE EYE. 49 



mass of cells running transversely, which is 

 intercalated between the sclera and the ciliary- 

 body, and encloses the angle of the anterior 

 chamber. These cells form a meshwork of 

 fibres which becomes the ligamentum pecti- 

 natum. 



The layer of closely packed endothelial cells 

 on the posterior surface of the cornea stops, 

 as a layer, at the angle of the anterior cham- 

 ber, but isolated endothelial cells lie in the 

 spaces of the ligamentum pectinatum, and a 

 thin endothelial layer with scattered nuclei 

 continues over the iris and out into the 

 pupillary membrane. 



The sphincter iridis and the ciliary muscle 

 develop late. The later stages of develop- 

 ment of the iris and ciliary body differ con- 

 siderably in the pig from those in man, and 

 are of no particular interest here. 



b. The pupillary membrane. When the 

 mesoblastic portion of the iris is first forming 

 it pushes out beyond the epiblastic portion 

 and rests upon the lens (Fig. 8). In this 



4 



