(c) Retina. 



The posterior half of a human eye was hardened in mercuric 

 chloride. Small pieces of the retina were removed, stained in Dela- 

 neld'H heematoxylin, embedded in paraffin, and sectioned. Fix to 

 the slide, and mount in balsam. 



Use high power. The following layers are made out, 

 named in order from before backward : 



(1) Internal limiting membrane. 



(2) Layer of nerve fibres. 



(3) Layer of ganglion cells. 



(4) Inner granular or molecular layer. 



(5) Inner nuclear layer. 



(6) Outer granular or molecular layer. 



(7) Outer nuclear layer. 



(8) Outer limiting membrane . 



(9) Layer of rods and cones. 



(10) Layer of pigment cells; this layer often remains 

 attached to the choroid, and may therefore not be seen in 

 your section. 



Sketch under high power. 



(d) Optic Papilla. 



The posterior part of a human eye was hardened in Miiller's 

 fluid. The optic papilla with a small portion of the posterior wall and 

 entering optic nerve was removed, stained in Delafield's haematoxy- 

 lin, embedded in paraffin, and sectioned. Fix and mount in balsam. 



Study first under low power. Note the dural and arach- 

 noidal sheaths of the optic nerve. They are continuous 

 with the sclerotic. The optic nerve fibres passing through 

 the lamina cribrosa and bending over and spreading out to 

 form the layer of nerve fibres of the retina, are to be observed. 

 Notice the excavation in the optic papilla. The nerve 

 fibres of the retina are on the anterior surface ; the rods 

 and cones point toward the sclerotic. The section may 

 show the artery centralis retinae in longitudinal, and 'some 

 of its branches in cross or oblique, section. Sketch under 

 low power. 



(e) Cochlea of a Guinea Pig. 



The cochlea of a guinea pig was hardened in Flemming's solu- 

 tion, decalcified in 1 % chromic acid, ami embedded in celloidiu. 



. 



^ ^ 



