On the intimate structure of bone, as composing the skeleton in the four great classes of animals, mammals, birds, reptiles, and fishes : with some remarks on the great value of the knowledge of such structure in determining the affinities of minute fragments of organic remains / by John Quekett.

  • Quekett, John, 1815-1861.
Date:
[1846]
Catalogue details

Licence: Public Domain Mark

Credit: On the intimate structure of bone, as composing the skeleton in the four great classes of animals, mammals, birds, reptiles, and fishes : with some remarks on the great value of the knowledge of such structure in determining the affinities of minute fragments of organic remains / by John Quekett. 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.

    19/31 (page 17)
    lUl the perennibranchiate Reptilia before enumerated present the same form of cells, but in none do they equal in size those of the Siren. The structure, then, of the bone of the perennibranchiate Reptilia may be characterized by the almost entire absence of the Haversian canals, except in tlie large bones, and by having their place supplied by enormously long and broad, and sometimes quadrilateral, bone- cells, with large canahculi, anastomosing freely with those of neigh- bouring cells : the canaliculi are large, like those of fish, but not so numerous as those of the ordinary reptiles, as may be seen by com- paring figs. 4, 5, and 6, with fig. 3, in Plate vii. In fact, everything agrees with the characters presented to us by the blood of these ani- mals. I have never yet seen the blood of the Menopome, Proteus, or Axolotl, but should infer, from the structure of their bone, that their discs or corpuscles, as they are termed, are not so large as those of the Siren. As some of the highest authorities in comparative ana- tomy are still at issue respecting the true class to which the Lepido- siren belongs, some regarding it as a reptile, others as a fish, I was anxious to ascertain what evidence of its true nature might be ob- tained from the structure of its bone ; and I may here state, that a thin fragment from the base of the cranium exhibits two forms of very large cells, the one of a quadrilateral figure, like those of the Siren, the other of an elongated form, similar to those of the Turtle, but much greater in breadth: the first kind were distributed irregularly, and at wide inter\'als apart from each other, whilst those of the second or elongated kind were arranged in parallel rows, with a dense net-work of canaliculi around them, so dense in some parts as almost to ob- scure the cell: in all these characters the structure agrees with that of the bone of the perennibranchiate Reptilia just described, no cells at all resembling them having as yet been found in any of the orders of fishes. The cells of the latter animals which come nearest to those of Reptilia are depicted in Plate vii. fig. 4; they are from the Conger Eel, and are elongated like those of the Turtle, but have not the breadth, nor so great a number of canaliculi as those of the latter animal, and they are so entirely different to the cells of any of the pe- rennibranchiate ReptiHa, that not a moment's hesitation need be required to .satisfy an inexperienced ob.server of their want of identity. The elongated cells are rarely to be found, except in the bones corn- posing the endo-skeleton of fishes: in the scales, and other thin plates of os.seous matter, the cells are of a small quadrilateral figure, and have but few canaliculi, as maybe seen in Plate viii. fig. ],