Essays and observations on natural history, anatomy, physiology, psychology, and geology / by John Hunter, being his posthumous papers on those subjects, arranged and revised, with notes ; to which are added the introductory lectures on the Hunterian collection of fossil remains delivered in the theatre of the Royal College of Surgeons of England, March 8th, 10th and 12th, 1855 / by Richard Owen.
- John Hunter
- Date:
- 1861
Licence: Public Domain Mark
Credit: Essays and observations on natural history, anatomy, physiology, psychology, and geology / by John Hunter, being his posthumous papers on those subjects, arranged and revised, with notes ; to which are added the introductory lectures on the Hunterian collection of fossil remains delivered in the theatre of the Royal College of Surgeons of England, March 8th, 10th and 12th, 1855 / by Richard Owen. Source: Wellcome Collection.
401/432 page 375
![answer the purpose of a defence from external violence to the contained parts. As the membranous skeleton is not stretchable, or has a sufficient firmness in texture not to yield beyond a necessary extent to the natural actions of the animal, and as, in such, the sections of motion are short, a pretty regidar form is preserved; for in every natural action there is such a relationship depending upon it, that no distortion of parts takes place, and only external violence deranges the form. A worm is just as regularly a formed animal as any other, although it varies more than those whose forms are more determined by [the harder nature of ] the skeleton. The cartilaginous skeleton differs from the former in the nature of its substance, as in the consistence whereby it retains its form; but there are considerable differences in the degree of consistence, and of course in the power of retaining form. This substance is introduced in various ways, but seldom alone, as we find in the membranous skeleton; in some animals there is more of it, and in some less, when the skeleton approaches nearer-to the membranous. Cartilage is used as an external covering, like a shell, as in those [Saljoa, Ascidia] which I have called the ' soft-shelled animals1.' Cartilage is used in the body of some animals as a fixed point for the muscles to act from. And as it is not so yielding as the membranous skeleton, it is composed of parts which are united to each other, ad- mitting of motion in those parts, and determining with more exactness the places of motion; although not perfectly, as it is elastic, yielding and recovering without the aid of antagonizing muscles. These unions mostly consist of membranes filling up the space between each cartilage; although in some the membrane makes a capsule. This mode of introduction of cartilage is principally in fishes ; and in some parts of other animals, such as the cartilages of the ribs in man. It gives more stability to the shape than membrane could, and admits of more variety of shape in animals. Cartilage.—This is semitransparent; of various consistence according to its use ; and is commonly of a determined shape or outline, seldom losing itself insensibly in the surrounding parts. Cartilages are of two kinds respecting the power of being changed for bone; one where it is forming the skeleton of many animals only before birth; the other where 1 [They answer to the Mollusca tunicata of Lamarck and Cuvier. The external skeleton, shown in the Hunt. Prep. Phys. Series, No. 76, is a dense gelatinous mem- brane, containing ' cellulose:' not true cartilage, but resembling it in physical properties.]](https://iiif.wellcomecollection.org/image/b21182656_0401.jp2/full/800%2C/0/default.jpg)
