THE EVIDENCE OF THE ORGANS OF VISION 



95 



(3) Optic fibre layer. 



(4) Thick inner nuclear layer. 



(5) Peculiar double-layered ganglionic layer. 



(6) External molecular layer. 



(7) External nuclear layer. 



(8) Mcmbrana limitans externa. 



(9) Layer of rods. 



(10) Pigment-epithelium. 

 He points out especially the peculiarity of layer (2) (2, Eig. 41), the 

 inner molecular, in which two rows of nuclei are arranged with great 



Fig. 41. — Retina and Optic Nerve of Petromyzon. (After Muller and 



Langerhans.) 



On the left side the Mullerian fibres and pigment-epithelium are represented alone. 

 The retina is divided into an epithelial part, C (the layer of visual rod-cells), and 

 a neurodermal or cerebral part which is formed of, A, the gauglion of the optic 

 nerve and, B, the ganglion of the retina. 1, int. limiting membrane ; 2, int. 

 molecular layer with its two layers of cells ; 3, layer of optic nerve fibres ; 4, int. 

 nuclear layer ; 5, double row of tangential fulcrum cells ; 6, layer of terminal 

 retinal fibres; 7, ext. nuclear layer; 8, ext. limiting membrane; 9, layer of 

 rods ; 10, layer of pigment-epithelium. D, axial cell layer (Axenstrang) in optic 

 nerve. The layer 6 is drawn rather too thick. 



regularity, the one row closely touching the mcmbrana limitans 

 interna, the other at the inner boundary of the middle third of the 



