I must allude to one or two points in the histology and physiology of the
organs of sense. The anterior continuation of the retina beyond the ora
serrata has been a subject of much discussion. If H. Muller and Kolliker
can be relied upon, this question is settled by recognizing that a layer
of cells, continued from the retina, passes over the surface of the
zonula Zinnii, but that no proper nervous element is so prolonged
forward.
I observe that Kolliker calls the true nervous elements of the retina
"the layer of gray cerebral substance." In fact, the ganglionic
corpuscles of each eye may be considered as constituting a little brain,
connected with the masses behind by the commissure, commonly called the
optic nerve. We are prepared, therefore, to find these two little brains
in the most intimate relations with each other, as we find the cerebral
hemispheres. We know that they are directly connected by fibres that
arch round through the chiasma.
I mention these anatomical facts to introduce a physiological observation
of my own, first announced in one of the lectures before the Medical
Class, subsequently communicated to the American Academy of Arts and
Sciences, and printed in its "Transactions" for February 14, 1860. I
refer to the apparent transfer of impressions from one retina to the
other, to which I have given the name reflex vision. The idea was
suggested to me in consequence of certain effects noticed in employing
the stereoscope.
Pages:
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300