BOO ISOLATION OF OPTIC NERVE-FIBRES OF MAMMALIAN RETINA. 
slightly obscured by adherent granules, probably the remains 
of connective substance of the layer. 
When the strengths of a third and a fourth were used, the 
bulb was allowed to remain in the fluid for thirty-six or 
forty-eight hours. 
Although both the ganglion-cells and the nerve-fibres in 
eyes, treated by the above methods, can be examined at once 
in glycerine; it may be found advantageous to subject the 
retina to other processes, through which the hardening nerve 
elements can now pass without injury. It may be placed 
flrst in water for a short time, and then may remain overnight 
in staining fluids, and finally be examined and preserved in 
glycerine, or, after being stained, it may be passed through 
alcohol and oil of cloves, and preserved in dammar varnish. 
The glycerine preparations show both the fibres of the optic 
nerve expansion and the ganglion-cells. The dammar pre¬ 
parations are useful as permanent specimens of the nerve- 
fibres. In either case some careful manipulation with needles 
is necessary to disentangle the nerve-fibres, a process which 
is particularly troublesome in the dammar preparations. Of 
all the staining fluids tried, a solution in water of anilin 
blue was found to be by far the best. For the nerve-fibres 
anilin blue alone is sufficient; for the ganglion-cells a double 
staining with anilin blue and eosin is useful. 
Eyes which have been placed in alcohol, as above directed, 
may be preserved for a long period in glycerine without the 
nerve-fibres or ganglion-cells suffering in the least. The 
effect of the glycerine by its affinity for water is to produce a 
complete collapse of the eye-ball. The lens preserving the 
shape of the anterior part of the bulb, the posterior half, is 
doubled up into the anterior half, forming a cavity at the 
bottom of w hich is the stump of the optic nerve. It is thus 
possible to prepare eyes at any time, and keep them ready 
for examination. He had excellent preparations of the optic 
nerve-fibres and ganglion-cells from the eye of a kitten, 
which, after being twenty-four hours in equal parts of me¬ 
thylated alcohol and water, had been kept sixteen months in 
glycerine .*—Journal of the Royal Microscopical Society. 
* The method is one that might be used for the examination of the 
retina of rare animals when the eyes have to be procured from a distance. 
After the remarkable observation of the anastomosis of the ganglion-cells of 
the elephant’s retina by Corti, to which there has been as yet no parallel, a 
further examination of the retina of that animal is very desirable. The 
eyes of elephants in a condition suitable for such an examination are not 
easily procurable, but by the use of the above method available specimens 
might be had from India. 
