Encyclopaedia Britannica > Volume 3, Anatomy-Astronomy

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ANATOMY.
Coxnpara- branches of science, by David Craigie, M.D., F.R.S.E., Fel-
tive lowofthe Royal College of Physicians, Edinburgh, and Hon-
Anatomy. orary Consulting Physician to the Royal Infirmary. Second
edition, enlarged, revised, and improved. Edinburgh and
London, 1848. Philadelphia, 1851. 8vo, pp. 1072.
8. The Cyclopcedia of Anatomy and Physiology. Edited
by Robert Bentley Todd, M.D., Professor of Physiology
and of General and Morbid Anatomy in King’s College,
London. London, vol. i., 1836; vol. ii., 1839; vol. iii., 1847;
vol. iv., 1852; large 8vo.
9. Elements of Anatomy, by Jones Quain, M.D. Fifth edi¬
tion, edited by Richard Quain, F.R.S., and William Shar-
pey, M.D., F.R.S., Professors of Anatomy and Physiology in
University College, London. In two vols. London, 1848.
10. On the Structure of the Lungs. Pesearches on the Mi¬
nute Structure of the Lungs in Man and the Principal Mam-
miferom Animals. By M. Le Dr Rossignol. Edinburgh Compara.
Medical and Surgical Journal,jo\. Ixxn, p. 88. July 1849.
11. The Human Brain, by Samuel Solly, F.R.S. Lon- v
don 1847, 8vo., pp. 628. . . - m ^
12. Plates of the Brain in Explanation of the Physical
Faculties of the Nervous System, by Joseph Swan. Lon¬
don, 1853. 4to. . . 7 tt/. 7
13. Archivfur Anatomic, Physiologic, und W issenschaft-
liche Medicin. Herausgegeben von Dr Johannes Muller.
Berlin, 1834-1853.
On the subject of Chirurgical and Topographical Ana¬
tomy, it would be difficult to refer to a more useful work
than the following, , , j
14. Surgical Anatomy, illustrated by lithograph coloured
engravincs ; by Joseph Maclise, Surgeon. London, 1849—
1851. Second edition, 1853. (d. C.)
COMPARATIVE ANATOMY.
PART I.
ANATOMY OF THE ORGANS OF RELATION.
CHAP. I. COMPARATIVE OSTEOLOGY.
Bones ge¬
nerally.
Red-Blooded Animals only can be said to possess
that assemblage of bones denominated skeleton; and as
in these the most constant part is the vertebral column,
it furnishes the general character of Vertebrated. The
shells of the Mollusca and the Crustacea have been ge¬
nerally regarded as a species of internal skeleton; and
in the circumstance of affording mechanical support and
external protection, they indeed resemble the skeleton of
the Vertebrata. But neither in mode of developement
nor in chemical constitution can they be regarded as of
the same nature. Hence it is only in the vertebrated
classes that it is requisite to study the peculiarities of the
skeleton.
In general characters the bones of the Mammalia re¬
semble those of the human subject. Like them, they are
white, firm, elastic, and incompressible. They consist
also of compact and reticular or cancellated tissue. In
the lower animals the latter kind of structure is in gene¬
ral coarser and looser than in man; and in the Cetacea
especially the cavities are large. In the carnivorous ani¬
mals the compact structure is exceedingly dense, and gives
the bone much greater weight than in other animals. In
the Cetacea also the acoustic or lithoid portion of the
temporal bone is of a marble hardness.
The bones of the Mammalia may, like those of man, be
distinguished, according to their mechanical form, into
long, flat, and short bones. Though the first class in ge¬
neral possess a medullary canal, this cavity is imperfect
or wholly wanting in the bones of the Cetacea and Am¬
phibia.
The cavities denominated sinuses are much more com¬
pletely developed in several of the Mammalia than in the
human skeleton. In the pig these cavities extend into
the occipital bone ; in the elephant they not only give the
frontal bone extraordinary protuberance, but they extend
into the parietal, temporal, and even the occipital bones,
and contribute much to augment the volume of the head.
In the ox, deer, and sheep, they communicate with the
cavity of the horns.
The bones of Birds are in general whiter, firmer, and
smoother than those of the Mammalia ; and they con¬
sist of a firm, compact substance, which is elastic and hard
in the bones of the trunk, and extremely brittle in those
of the extremities. With the exception also of some of
the thin, flat bones, as the sternum, they consist of thin,
compact walls, inclosing large capacious cavities, which
contain not marrow, but air, and which communicate by
one or more minute holes with the windpipe and lungs.
While these cavities, which may be regarded as the most
perfect and advanced form of sinuses, diminish consider¬
ably the weight of the whole skeleton, by the density and
completely cylindrical shape, they rather augment the
strength. In the chick, and at birth, the bones are ho¬
mogeneous and without cavities; afterwards they contain
marrow; and eventually this disappears and gives place
to air.
The bones of the Reptiles are not remarkable in any
respect, unless in being void in general of medullary ca¬
vity. The absence of this canal was originally observed
by Caldesi, and afterwards by Cuvier, in the tortoise; by
Troja in the bones of the frog and toad; and by Carus in
those of the turtle. In the crocodile, however, and in
several of the lizard family, they are large and distinct.
The bones of Reptiles also are less firm than those of Birds
and Mammals.
The bones of Fishes are remarkable for great softness,
flexibility, and elasticity. Those of the lamprey, shark,
ray or skate, and sturgeon family, are soft, flexible, sec-
tile, of a bluish white colour, translucent, and so elastic
that a cutting instrument forced into them is speedily re-
truded by the resilient nature of the bony matter, from
these characters, the bones of these families have been
regarded as cartilaginous, and the fishes themselves have
been distinguished by this character. (Pisces cartila-
ginei, pisces chondropterygii.) In the other fishes,
the bones, though softer than those of Mammals, Birds,
and Reptiles, present a greater degree of firmness and so¬
lidity, are whiter and more opaque, and are much less
sectile, than those of the cartilaginous division. As in this
respect, therefore, they approach the genuine bone of the
Mammals, these are distinguished as fishes with osseous
skeletons. (Pisces ossei.)
The bones of both classes of fishes consist of a large
quantity of gelatine, with a small proportion of phosphate