an image almost equal in vividness to itself; and consequently when we see with one eye only, we may, however, have pictures in both eyes.”  Hartley, in 1784, had anticipated many of the doctrines which have since been systematized into the theory of reflex actions, and with 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 the movements of organization, as profound as in the fall of a stone or the formation of a crystal.