th which I have
attempted to associate this act of reflex vision. My sixth experiment,
however, in the communication referred to, appears to me to be a crucial
one, proving the correctness of my explanation, and I am not aware that
it has been before instituted.

Another point of great interest connected with the physiology of
vision, and involved for a long time in great obscurity, is that of the
adjustment of the eye to different distances. Dr. Clay Wallace of New
York, who published a very ingenious little book on the eye about twenty
years ago, with vignettes reminding one of Bewick, was among the first,
if not the first, to describe the ciliary muscle, to which the power of
adjustment is generally ascribed. It is ascertained, by exact experiment
with the phacueidoscope, that accommodation depends on change of form of
the crystalline lens. Where the crystalline is wanting, as Mr. Ware long
ago taught, no power of accommodation remains. The ciliary muscle is
generally thought to effect the change of form of the crystalline. The
power of accommodation is lost after the application of atropine, in
consequence, as is supposed, of the paralysis of this muscle. This,
I believe, is the nearest approach to a demonstration we have on this
point.

I have only time briefly to refer to Professor Draper's most ingenious
theory as to the photographic nature of vision, for an account of which
I must refer to his original and interesting Treatise on Physiology.

It were to be wished that the elaborate and very interesting researches
of the Marquis Corti, which have revealed such singular complexity
of structure in the cochlea of the ear, had done more to clear up its
doubtful physiology; but I am afraid we have nothing but hypotheses for
the special part it plays in the act of hearing, and that we must say
the same respecting the office of the semicircular canals.

The microscope has achieved some of its greatest triumphs in teaching
us the changes which occur in the development of the embryo. No more
interesting discovery stands recorded in the voluminous literature
of this subject than the one originally announced by Martin Barry,
afterwards discredited, and still later confirmed by Mr. Newport and
others; namely the fact that the fertilizing filament reaches the
interior of the ovum in various animals;--a striking parallel to the
action of the pollen-tube in the vegetable. But beyond the mechanical
facts all is mystery in th