On diseases of the eye, as a guide in the study of pathology / by Arthur Jacob, M.D.

  • Jacob, Arthur.
Date:
[1841?]
Catalogue details

Licence: Public Domain Mark

Credit: On diseases of the eye, as a guide in the study of pathology / by Arthur Jacob, M.D. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    9/20 (page 7)
    is perhaps the most beautiful specimen of vascularity, in all its perfection, which meets the eye of the phy- siologist ; with it the artificial injected preparations of the anatomist cannot, for a moment, compare ; yet we scarcely find it made an object of study by persons professing to investigate the state of the circulation in the capillaries. In the actions of the iris so favoui'ably exposed for observation in the aqueous humour, and beneath the cornea, the phenomena, which accompany muscular contraction, may be studied with greater ad- vantjige than in any other part of the body, because here alone can we see the naked organ undergo its changes of form and perform the duties assigned to it. Elsewhere we perceive the effect of this truly wonderful, this almost mysterious vital action, but here we see the act itself, and can trace it to the cause which elicits it. If the action of the heart could be viewed through a large transparentlenticular window in the chest, we should most probably possess much more accurate information respecting it; hidden as it is from view, we can now only make reasonable guesses as to the manner in which it accomplishes the objects for which it was designed. I need not say that I am aware that the actions of the iris not being in strict accordance with the laws which are supposed to regulate muscular contraction in general, that organ has often been held to owe its changes in form to other causes. This discrepancy, however, appears to me to prove not that the actions of the iris are inde- pendent of muscular contraction, but that the theories prevalent in the schools are not founded in truth : it is not the contractions and dilatations of the pupil which are anomalous, but the inferences drawn from superficial inquiries which are incorrect. In enumerat- ing the instructive lessons to be derived from obser- vation of the actions of the iris, and which are not to be learned from observation of any other part of the body, the effect of the active principle of the Atropa Belladonna in causing dilatation of the pupil must not be forgotten. The whole range of physiological ex- periment does not afford a more interesting fact, or one more difficult of explanation, notwithstanding the implicit confidence reposed in the opinions generally entertained respecting the phenomenon. The influ- ence of a narcotic poison on the functions of an organ through the nerves is here unequivocally displayed, and the importance of the fact that such influence can be exercised through that channel is unequivocally proved. 1 have endeavoured to point out very briefly the