VETERINARY OPHTHALMOLOGY. 107 



Extends from the optic nerve to the ciliary processes, 

 where it is called the ora serrata. Consists of ten 

 layers. (1) The internal limiting membrane, separates 

 the nerve fiber layer from the vitreous, and the fibers 

 of Mtiller terminate in this layer. (2) The nerve fiber 

 layer, consists of the s^xis-cylinder of the optic nerve 

 fibers, which run in a radiating direction to the ora 

 serrata, where they terminate. At the macula lutea 

 these fibers are bent into arches, and this arrangement 

 permits a larger number to reach the fellow spot -than 

 if they approached in a radiating direction. (3) IVie 

 layer of ganglion cells, composed of multipolar cells, 

 each with a nucleus and nucleolus. A nerve fiber en- 

 ters each of these cells, and one or more prolongations 

 •extend out into the inner molecular layer. These 

 ganglionic cells are an-anged closer around the optic 

 nerve than at the ora serrata.- (4)^ The internal tnolecu- 

 lar layer, one of the thickest, granulous in appearance. 

 Consists principally of fine fibers from the layer of 

 ganglion cells. (5) The internal granidar layer, com- 

 posed of two kinds of cells witli nuclei. The larger are 

 nerve cells, having two offshoots, one passing into the 

 inner granular layer, anastomosing with offslioots of the 

 ganglionic cells, the other out to the external molecular 

 layer and supposed to anastomose with fibers from the 

 laver of rods and cones. The smaller cells of this 

 layer are connected with the fibers of Mliller. (6) The 

 ■external molecular layer. Very thin and is made up of 



