Observations on the arrangement of the fibres in the optic nerve of the loligo and other animals.

  • Power, John H. (John Hatch), 1806-1863.
Date:
1842
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the arrangement of the fibres in the optic nerve of the loligo and other animals. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    complexity, particularly at the extremities of that body ; in these situations the fibres are so grouped together, that their arrange- meut is not so satisfactorily seen as in the central portion of the nerve ; nevertheless, even here, on examining the surface of the ganglion with a lens, I could perceive the fibres running for a given distance upon it, converging towards a point, and soon be- coming lost by indigitating with other fibres on this body, and so eludingfurtherexamination. Any attempt to tracethem into the ganglion itself would, I think, be useless, as this body is exceed- ingly soft and pulpy, particularly in the interior. In the centre of the nerve, however, there can be no doubt of the existence of the interlacing fibres. The peculiarity I have described seems to be a characteristic feature in this entire group of animals. I have recently had many opportunities of examining this nerve in a great variety of animals, and in almost every instance I was able to detect such a disposition of many of their fibres, as I conceive serves the same purpose as that in the Loligo. In detailing the result ofthe.se examinations, it will be necessary to advert to the optic tract and commissure, as well as to the nerve itself. I will, however, avoid as much as possible* unne- cessarily dwelling on any thing connected with the anatomy of these parts, and shall merely confine my remarks to what more immediately bears upon the matter at present under considera- tion, particularly as my friend Dr. Mayne is at present engaged in making a series of examinations into the origin and structure of the optic nerves of various animals, the result of which I feel assured, when published, will prove both iiiterestingand instructive. In the Hake and Cod, as in other osseous fishes, there is no commissure, but the nerves decussate with one another without any interlacement of their fibres, and so terminate in the eyes of op- posite sides I have observed, however, in the substance of each nerve, close to its connexion with the brain, an apparent enlarge- ment, and at this spot I was able to discern the fibres of which it is composed, irregularly interlacing with each other in the interior of the nerve. The superficial fibres in the Cod run spi- rally onward towards the eyeball, and just where the nerve