Montlilv Micro-^copicall 
Journal, Oct. 1, 1869. J 
Ciliary Muscle in Birds. 
205 
where, as Crampton and others had pointed out, the ciliary muscle 
being distinctly striated, its beginning and end may be tolerably 
easily made out. It was in the ' Ophthalmic Eeview ' (for, I think, 
the year 1865) that, in a paper objecting to Helmholtz's and 
Donders' notions of the cause of accommodation, I first published 
my remarks on the relations of the ciliary muscle : the eye of the 
ostrich having been taken as the example. The subject, however, 
has not received the attention it deserves from physiologists ; and 
with a view to show that at least in birds, accommodation must be 
effected in a totally different manner from that proposed by 
Donders, I am led to bring the question once more under the 
notice of histologists. I propose from time to time, as I may have 
leisure, and as the Zoological Society may be able to furnish me 
with "birds' eyes," to describe the relations of this remarkable 
muscle in various birds, and first in the green-breasted pheasant, 
the eyes of which were kindly placed at my disposal by Dr. James 
Murie. 
The description of the ciliary muscle in most of the text-books 
is, so far as it apphes to birds, extremely misleading and inaccurate. 
It is generally described, both for man and birds, as a ring of mus- 
cular or fibrous structure extending all round the eye at the line of 
union of the sclerotic and cornea. But in birds it is really much 
more than this. 
If we take only the bird which forms the subject of this note, we 
find that the ciliary muscle is much more than a mere ring." It is in 
some measure almost a distinct coat. It may be described as a zone 
or belt of muscular tissue (holding much the same sort of proportion 
to the orb that the Tropic of Cancer does to the globe), whose fibres 
run forwards to the line of junction of the cornea and sclerotic, and 
extend backwards between the sclerotic and choroid for some lines. 
In section made along the long axis of the eye, the ciliary muscle 
would have an irregular pear-shape, the head of the pear being at 
the sclerotico-corneal junction, and the stalk some lines behind and 
between the sclerotic and cornea. The fibres are broad and somewhat 
flat, of the usual faintly-yellow colour (caused by steeping structure 
in chromic acid), and very beautifully striated, and they pass in a 
regular stream from behind forwards, and from without obliquely 
inwards, till they end generally in the sclerotico-corneal junction. 
All the fibres do not pass into this fine of junction. The muscle 
is provided with a very tough and dense sheath of connective 
tissue, which is so loaded with irregular pigment-cells as to render 
the definition of the fibres at first rather difficult. But this sheath 
is more than a mere envelope. It increases in thickness and tough- 
ness at the sclerotico-corneal junction, and along the anterior half of 
its length (along the pear-shaped part) it gives insertion to the 
anterior extremity of many of the muscular fibres which are tra- 
