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MANUAL OF PHYSIOLOGY. 



the central point (fovea ceutralis), which they avoid by passing 

 on each side of it. 



Next to the fibres comes a layer of nerve cells, these seem com- 

 monly to have one pole connected with a fibre from the optic 



FIG. 229. 



Showing the course of the fibres of the optic nerve N, as they pass along 

 the inner surface of retina n, to meet the ganglion cells, whence special 

 communications pass outwards to the layer of rods and cones in the pigment 

 layer p, next the choroid c. 



nerve, while from the other side two or three poles send processes 

 into the other layers of the retina. 



Then comes an indistinct layer made up of granular material 

 and two layers of peculiar nuclear bodies, with a layer of granular 

 material between them. 



Outside of these, and separated by a fine limiting membrane, is 

 the most important layer of the retina. It consists of a layer of 

 rods and cones which are connected with those parts of the retina 

 already named, and seems to project into the protoplasm of pig- 



