200 



HAND-BOOK OF PHYSIOLOGY. 



1. Membrana limitans internal a delicate membrane in contact with 

 the vitreous humor. 



2. Fibres of optic nerve. This layer is of very varying thickness in 

 different parts of the retina: it consists chiefly of non-medullated fibres 

 which interlace, and some of which are continuous with processes of the 

 large nerve-cells forming the next layer. 



FIG. 370. Diagram of the retina. A, connective tissue portion; B, nervous portion (the two 

 must be combined to form the complete retina); aa, membrana limitans externa; 6, rods; c, cones: &', 

 rod-granule; c'. cone-granule; both belonging to the external granule layer: e< Mailer's sustentacular 

 fibres, with their nuclei e'; d, intergranular layer;/, internal granule layer; g, molecular layer, con- 

 nective-tissue portion; <?', molecular layer, nerve fibril portion; /i, ganglion cells; h', their axis-cylin- 

 der process; i, nerve-fibre layer. (Max Schultze.) 



3. Layer of ganglionic corpuscles, consisting of large multipolar nerve- 

 cells, sometimes forming a single layer. In some parts of the retina, 

 especially near the macula lutea, this layer is very thick, consisting of 

 several distinct strata of nerve- cells. These cells lie in the spaces of a 

 connective-tissue framework. 



