"^ou^nli. oc^ri^^^^^^ Ciliary Muscle in Birds. 207 
be wrong. I don't think it is. But supposing it right, I would ask, 
What effect can this muscle have on the consistence of the lens, from 
which it is so distant ? How can it advance the lens through the 
action on choroid, to which its attachment is so far posterior to the 
lens ? and lastly. What can be the effect of the contraction of so 
important a muscular structure but to bend in the border of the 
cornea, and thus increase the curvature of the object-glass of the eye ? 
Its origin — the sclerotic — is unyielding ; its insertion — the cornea 
— is. The liquid of the eye resists the inward pressure of the cornea, 
and driving its central part out, still more increases the curvature. 
Lastly, in the elastic lamina of the cornea do we not see the anta- 
gonist of this powerful muscle. Birds must necessarily possess 
greater power of focal accommodation than man, but why should 
the mechanism by which that accommodation is obtained be so 
different from that of man as the views of Helmholtz would lead 
us to suppose, if we believe the ciliary muscle of birds to operate as 
I have suggested ? 
