G06 



THE EYE. 



over tlie pigment-cells send fine non-pi gmented offsets between the 

 external retinal elements. When the choroid is detached these offsets 



Fis. 417. 



Fig. 417. — The Posterior Half of the Retisa of the Left eye tieweb from 

 BEFORE (Henle). Twice the natural size, 

 s, cut edge of tlie sclerotic ; cli, choroid ; r, retina : in the interior at tlie middle the 

 macula lutea with the depression of the fovea centralis is represented by a slight 

 oval shade ; towards the left side the light spot indicates the colliculus or eminence at 

 the entrance of the optic nerve, from the centre of which the arteria centralis is seen 

 sending its branches into the retina, leaving the part occupied by the macula com- 

 paratively free. 



are ruptured and the pigmentary laj'cr comes away with it. The inner 

 sm-face of the retina is smooth : on it the following objects may be seen 

 (fig. 417). In the axis of the ball is a yellow spot — macula lutea (limlms 

 luieus, Summerring) — wliich is somewhat elliptical in shape, and about 

 2'oth of an inch in diameter : in the centre of this, again, is a slight 



Fiff. 418. 



Fig. 418. — Section through the Middle of the Optic Nerve and the Tunics of the 

 Eye at the Place of its Passage through them (Ecker). 2 

 «, arteria centralis retinas ; 6, fasciculi of optic nerve fibres with neurilemma ; c, sheath 

 of the opti<; nerve, passing into c , the sclerotic coat ; c", membrana fusca ; d, clioroid ; 

 <') /> layer of rods and cones ; g, the nuclear layers ; h, layer of nerve-cells ; i, layer of 

 nerve-fibves ; Ic, colliculus or eminence at the entrance of the optic nerve ; I, lamina 

 cribrosa. 



