228 PROCEEDINGS OF SOCIETIES. 
course of which he said—‘I would not Have brought forward a 
subject so dry and technical, were it not for the fact that the 
structure of the iris and the ciliary muscle is not alone interesting 
to the histologist, but it is one of those instances in which the 
microscope may be brought to bear upon physiological studies ; 
and it seems to me that if we can in any way give the work thus 
a more practical turn, so as to bring it out of the range of mere 
amusement, it will be a very useful thing. I wish to direct 
attention more particularly to the action of these muscles in 
accommodating the eyes for objects near and far. It is, perhaps, 
unnecessary to say that what is meant by the accommodative 
action of the eye is its power of adaptation to the various dis- 
tances of objects. It is difficult to see objects near and far at the 
same time distinctly ; it is a matter of very familiar experiment, 
and it is quite evident that some change does take place in the 
eye itself, either in the shape of the eye or in some other way, 
but how that change is effected is and has been a matter of con- 
siderable doubt, and explanations of it have been offered both by 
anatomists and by physicists. Helmholtz says that the change 
consists in an alteration in the shape of the lens, that it is 
pressed upon laterally at its peripheral edges, and that it bulges 
in consequence and is rendered thus more convex, and that in 
this way it accommodates itself to the various distances of objects. 
It is precisely upon that point that I want my paper to bear. 
“The ciliary muscle is attached at the junction of the cornea 
with the sclerotic coat, and is a membrane spreading out in a 
fan-like form, and passing into the choroid and the ciliary pro- 
cesses. If you look at this diagram of horizontal section of the 
eye, you will see that there is no very obvious way in which this 
muscle can act in the manner described, for since it never gets 
into any contact with the lens it is difficult to see how the contrac- 
tion of this muscle can make the lens more convex by pressure. 
The difficulty, then, was to make the anatomical structure of the 
ciliary muscle (which requires a 4 inch power for its examination) 
coincide with the physical theory of Helmholtz. The lens is 
clear and structureless, and if such a change takes place in its 
form, it must be by the external action of some muscles such as 
these. Then came Miller, who made a number of observations 
which showed sphinctral or circular muscular fibres which he 
considers can have that action. In the sections and drawings he 
shows the cut ends of fibres, and these, it is asserted, are true 
sphinctral fibres encircling the lens as a compressor. I have 
myself examined a considerable number of sections under 1, 4, 
and +4, objectives, but in no case have I been able to detect the 
existence of anything which I can consider a sphinctral muscle. 
Mr. Lockhart Clarke also has made a careful examination of 
them, but could detect nothing of the sort. Cut ends were 
visible, but they were not the ends of a series of fibres having a 
circular course, if they be the ends of muscular fibres at all. In 
man the ciliary muscle is formed of soft, unstriped fibres, so that 
