File:Image from page 377 of "On the anatomy of vertebrates (electronic resource)" (1866) (14753215254).jpg

Identifier: b20416039_001 Title: On the anatomy of vertebrates [electronic resource] Year: 1866 (1860s) Authors: Owen, Richard, 1804-1892 Subjects: Anatomy, Comparative Vertebrates Fishes Reptiles Mammals Birds Publisher: London : Longmans, Green Contributing Library: Wellcome Library Digitizing Sponsor: Wellcome Library

View Book Page: Book Viewer About This Book: Catalog Entry View All Images: All Images From Book

Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image: les, both of which microscopic structures are moreeasily demonstrated in the present than in the higher classes ofVertebrata. Each twin-corpuscle is surrounded by a circle ofcylindricules. The primitive nerve-fibres radiate over the cylin-dricules, without anastomosing, and terminate in free ends, not byloops, at the basis of the ciliary zone. A delicate but well-defined raised rim or i bead runs along both the anterior marginsof the retina, and along those which form the falciform slit. The crystalline lens (cf) is spherical, or nearly so, large, firm,with a dense nucleus: it is almost buried in the vitreous humour,where it is steadied by the attachment of the falciform ligamentto its thin capsule: the fore part projects through the pupilagainst the flat cornea, and so nearly fills the anterior chamber,that but a very small space is left for aqueous humour. In thecod and other Gadidce the fibres of the lens converge, like the 1 xx. vol. iii, p. 144; eye of the Bonito, prep. no. 1651.

Text Appearing After Image: ORGAN OF SIGHT IN FISHES. 333 217 mSi- ■■a :i; f Fibres of lens, highly magnified, showing inter-locking of their toothed margins, ccxni meridians of a globe, to two opposite points or poles of the sphe-roid : in the Salmonidce and Shark, they converge to a linear tractor septum at each pole, as in fig218. In the fibres of the lensof a cod Brewster discoveredthe marginal teeth, like those ofrack-work, by which the fibresare interlocked together, as infig. 217. This acute observer computesfive millions of fibres and sixty-two thousand five hundred mil-lions of teeth in the lens of a cod:yet in the living and fresh statethis organ is transparent. The radiating fibres and elong-ated cells of the hyaloid tissue,1with the interstitial i vitreoushumour, present a firmer con-sistency than in the human eye,and show their intimate structure and arrangement more clearlyunder the microscope than in Mammalia. The membranes situated between the retina and sclerotica,called collectively ( choro

Note About Images