RETINA OF LATERAL EYES OF SPHENODOX PUNCTATUS. 309 
finer details of the cones were clearly expressed, the para- 
boloid, the ellipsoid and the outer segment all staining iu 
different tints as will be described in due course. 
Picro-nigrosine, though rather erratic in its staining effects, 
was in places excellent, and some of my best sections were 
prepared in this way, the details showing well in red and 
grey colours. 
The oil-globules remained unstained in all these prepara- 
tions. 
(c) Aceto-bi chromate Material. — The eyes of Splieno- 
don VI had been fixed in acetic bichromate of potash and 
proved most satisfactory. The layers of the retina separated 
less than in the case of material fixed in the other fluids. The 
sections stained readily and their histology was excellent. 
My most successful preparations were those stained in 
bulk with borax carmine and on the slides afterwards with 
picro-indigo-carmine, when the general appearance was as in 
those fixed in Zenker’s fluid. 
The oil-globules remained unstained after acetic bichro- 
mate as after Zenker. 
I should like to take this opportunity of expressing my 
indebtedness to Mr. Charles Biddolph, Prof. Dendy’s labora- 
tory assistant, for his skilful assistance ill preparing the 
sections. 
III. Descriptive and Critical Account of the Retina, 
a. General Account. 
The retina of the preserved eye, as in other animals, very 
readily separates into two layers, the pigment epithelium 
remaining attached to the choroid and the inner portion 
shrinking away from it. 
On cutting the eyeball at right angles to the optic axis and 
looking at the inner surface of the posterior half, a small pit 
can be distinctly seen lying near the optic axis and at a 
distance of about 3*5 mm. from the point of entrance of the 
