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XXII. On Single and Correct Vision, by means of Double and Inverted Images on the Retinœ
Published online by Cambridge University Press: 17 January 2013
Extract
In entering on a question which may be said to occupy a portion of the debateable land between Physiology and Metaphysics, it seems, in the first place, necessary to state with precision the nature of the difficulty, which has long been felt on this subject, and endeavour to determine the degree to which it is reasonable to expect, that this difficulty may be removed; and on these points there is such a discrepancy of opinion, even among the latest and most esteemed authors, as obviously to make farther inquiry desirable.
No one can be more thoroughly convinced than I am, of the utter futility and absurdity of all attempts “to shoot the gulf which separates the sensible world from the sentient soul.” In all our inquiries in the Physiology of the Nervous System, as connected with mental acts, we must keep in mind, that the end of these inquiries can only be, to determine the physical conditions under which the different mental phenomena take place; and those under which, when they have taken place, they affect the different organs of the body. The question, how it comes about, that when those conditions are fulfilled, these results follow, must be held, in every case, to be beyond our powers.
- Type
- Research Article
- Information
- Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 13 , Issue 2 , 1836 , pp. 472 - 493
- Copyright
- Copyright © Royal Society of Edinburgh 1836
References
page 474 note * Lect. 29.
page 476 note * Inquiry into the Human Mind, &c. Sect. 17, ad fin.
page 480 note * The term optic lobe is here used as a short expression for that portion (perhaps not yet absolutely determined) of the contents of the cranium, from which the optic nerves originate, and on which their sensibility depends.
page 481 note * This affection is sometimes quite transient; but in other cases, as I have myself known, it is permanent, at least for weeks together.
page 482 note * Anat. Comp. Leç. xii. Art. 2. It is true that the axes of the two eyes, at least in some fishes and reptiles, may be brought to bear on the same objects, if very distant, but as the vision of very distant objects is seldom requisite for these animals, it is probable that they are not habitually guided by simultaneous impressions on the two eyes.
page 486 note * See Recherches Experimentales, &c. p. 150, et seq.
page 487 note * See Plate XVI. Fig. 2. of this volume.
page 487 note † See Anat. Comp. du Cerveau, Plates vi. vii. Figs. 149, 151, 159, 165, 170, 181, 188-89, and 193; and PI. XVI. Fig. 3. of this volume.
page 488 note * Plate XVI. Fia: 4.
page 490 note * Cuvier. Rapport sur l' Anat. Comp. du Cerveau, &c. par Serres, in latter work, pref. p. 26.
page 490 note † Cuvier, Leçon 12, Art. 2. ‡ Serres, p. 326, et seq.
page 490 note § Recherches Experimentales, &c. p. 121.
page 492 note * Outlines of Human Pathology, p. 202.
page 492 note † “The two cords of the spinal marrow do not cross, but merely the middle or pyramidal fasciculi of each, which give origin to the Crura cerebri by expanding and becoming broader.”—Tiemann's Anatomy of the Fœtal Brain, Translated by Bennett, p. 144. I am aware of the difficulty of tracing the course of the fibres at the medulla oblongata, and what Sir Charles Bell describes, I believe correctly, decussating fibres behind the pyramids; but all are agreed that there are fibres in this part which do not decussate.