102 
PHYSIOLOGICAL ACTION OF ATROPINE. 
I have found that in the sturgeon, the optic fibres which 
extend in a very elegant manner in the form of a double 
comb, possess very strong outlines in a great part of the 
retina. The retina of the Plagiostoma also, both sharks and 
rays, contains fibres of a breadth of as much as O Oi mill., 
which exhibit all the characters of the varicose fibres with 
double outlines which occur in the nervous centres. Lastly, 
I have observed that in the eyes of many dogs, the optic 
nerve is still white at its entrance into the eye, and that it is 
only in the retina that the nervous fibres become pale and 
transparent. But the change takes place very soon after the 
entrance of the optic nerve, whilst in the fishes just men- 
tioned, the fibres with double outlines extend over a great 
part of the retina, and only pass by degrees to the aspect of 
the pale fibres. In a physiological point of view it is remark- 
able that in the fishes of which I am speaking, notwithstand- 
ing the double outlines of the nervous fibres, the retina ap- 
pears to be tolerably transparent during life, whilst in the 
rabbits and dogs it is opaque and white, in the whole extent 
of the fibres with double outlines. In the former case the in- 
fluence upon the sight does not appear to be important, but 
in the latter the perception of light must be hindered or dis- 
turbed as far as this peculiarity of the fibres extends ; and 
the ophthalmoscopic effect of the bottom of the eye, and espe- 
cially of the entrance of the optic nerve, must present remark- 
able modifications in all the animals in which a state similar 
to that which has long been known in the rabbit exists. — 
Comptes Rendus . 
ON THE PHYSIOLOGICAL ACTION OF ATROPINE IN 
DILATING THE PUPIL. 
By George Harley, M.T)., Teacher of Practical Physio- 
logy and Histology, in University College, London. 
During the perusal of a paper of great merit (in the July 
number of the Edinburgh Medical Journal ), on some of the 
cases treated at the Eye Infirmary,* I came upon a very 
ingenious theory with regard to the action of atropine and 
belladonna in dilating the pupil. After a lucid description, 
throughout which the physiological effect of these substances 
upon the iris is ascribed, not to their producing paralysis of 
* ‘Report of Cases occurring at the Edinburgh Eye Infirmary.’ By 
Robert Hamilton, M.D., F.R.C.S.E., and Benjamin Bell, Esq., E.R.C.S.E. 
