i 
889 
Extracts from British and Foreign Journals. 
ISOLATION OF THE OPTIC NERVE-FIBRES AND GANGLION- 
CELLS OF THE MAMMALIAN RETINA* 
Dr. George Thin, in an article in the Journal of Anatomy 
and Physiology , says that the isolation of the ganglion-cells 
and optic nerve-fibres of the retina has certainly not been 
found by histologists to be invariably an easy task, and he 
can testify from experience that methods which are well 
fitted for the observation and study of other parts of the 
retina, destroy the processes of the ganglion-cells and the 
nerve-fibres. Max Schultze has acknowledged this difficulty 
in his article on the retina in Strieker's ‘Handbuch,’ published 
in 1872. Dr. Thin is induced, therefore, to believe that the 
publication of a method by which he found the isolation of 
these elements singularly easy, may be considered justifiable. 
The method holds good for the retina of the cat and the 
sheep; but there can be little doubt that it will prove equally 
useful in the case of many other mammalia. His observa¬ 
tions have been limited to the eyes of these two animals. 
It is well known that if a sheep's eye be placed in a suffi¬ 
cient quantity of alcohol for twenty-four hours, and at the 
end of that time be laid open, and the retina be then ex¬ 
amined in glyceiine, the optic nerve-fibres and ganglion-cells 
will be found more or less well preserved. But it is a matter 
of no small importance to regulate the strength of the alcohol, 
and diluted alcohol will be found more useful than strong 
alcohol. A mixture of equal parts of methylated alcohol and 
water is a strength that he used for some time, with such 
excellent results that he adhered to it during most of the 
time that he was engaged in examining this part of the retina ; 
but latterly he found that, in most respects, a weaker strength 
secured as good preparations, and for some purposes pro¬ 
duced better ones. For the preservation of the processes of 
the ganglion-cells, mixtures of one part of methylated alcohol 
with two of water, and one of methylated alcohol with three 
of water, are peculiarly well adapted. The fibres of the optic 
nerve expansion are well seen, whichever of these strengths 
is used. They may be isolated in great numbers, and for 
great lengths, after the bulb has been in equal parts of water 
and alcohol. When only a fourth strength of alcohol was 
employed, the nerve-fibres were, unless well teased out, 
# * Journ. Anat. and Phys.’ (Humphry), xiii. (1879), p. 139. 
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