Report on the progress of human anatomy and physiology in the year 1844-5 / [Sir James Paget].
- James Paget
- Date:
- 1846
Licence: Public Domain Mark
Credit: Report on the progress of human anatomy and physiology in the year 1844-5 / [Sir James Paget]. Source: Wellcome Collection.
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![skin of frogs when they breathe in pure oxygen, held over water, so that the carbonic acid they produce may be absorbed. In a few hours the blackish- green elongated marks, extending backwards and downwards from the eyes, become lighter and greener. Then for several days the change goes on more slowly, but at the end of twelve days it is very distinct in ail the spots; the dark semicircular marks on the thighs can then hardly be seen The development of epidermis has been described by Mr. Erasmus Wilson* as consisting essentially in—1st, the production of “primitive granules” in the blastema; 2d, the collection of four, five, or six of these into “ aggregated granules,” which become the nucleoli of the complete cells ; 3d, in the ar¬ rangement of a single tier of aggregated granules around each of these first aggregated granules, so as to form an oval or circular mass, a “ nucleated granule,” the nucleus of the complete cell; and 4th, the production of an¬ other tier of aggregated granules around the nucleated granule, forming a transparent border around it, around which border there is probably a cell- membrane, forming the proper epidermis cell or “nucleolo-nucleated cell.” The growth of the cell he believes to be due to successive repetitions of the same process in the development and growth of aggregated granules within it, the full-grown cell containing secondary and tertiary cells and bodies in all the four stages of development above mentioned. Cartilage. M.Valenciennest has made an extensive examination of the struc¬ ture of the cartilages in mollusca and cartilaginous fish, but the only facts which it appears important to state here are —1st, that the cartilage cells are generally arranged in such regular plans that it would be possible to determine by mi¬ croscopic examination the order, or even the genus, of an animal, from the character of its cartilages ; 2d, that none of the cartilage cells have, in any species, canaliculi communicating with them ; and 3d, that gelatine, not chon- drine, is abundant in the cartilages of cephalopods. Bones: chemical analysis. A number of analyses of bones of various ani¬ mals have been made by Dr. Stark.\ He shows that, besides their marrow [i. e. I suppose, all the fat that can be easily scooped out of the cancellous tissue], the bones of mammalia contain from 13*5 to 29 2 per cent, of fatty matter. The solid part of the shaft of the canon bone of a sheep contained 4*3 per cent. The bones of almost all birds under one year old contain an oleo-albuminous (?) matter, which, as the bird grows older, is absorbed. No less than 232 analyses of various bones from all the vertebrate classes are given, to show the proportions of animal and earthy matters; and the result is, that in all bones the proportion is nearly the same, the average proportion for all being 66-09 of earthy matter to 33-91 of cartilage. No confirmation is afforded of the notion that the proportion of earthy matter is the larger the higher the animal is in the scale of creation, for the largest proportion (68*74) was in the true bones of cartilaginous fishes—the smallest (619 to 62-3) in the bones of the bear and marmozette monkey The proportion of earthy matter appeared a little greater in the wild than in the domesticated mamma¬ lia. There was no evidence found of its increasing with age in either men, cows, or sheep. Neither did the hardness, or inflexibility, or want of trans¬ parency of bones appear to be dependent on the earthy matter being present in a very large proportion, but on the mode in which the textures of the bone were held together. Structure. Mr. Goodsir§ states that in the cavity of each bone-corpuscle, but not extending into the canals, there is “ a little mass of nucleated cells of great transparency.’’ This he regards as the germinal centre of the texture or * Proceedings of the Royal Society, No.Gl, June 19, 1845 ; and Philosophical Mag., Feb. 104G. t Comptes Rend us, 25 Nov. 1844. j Edinb. Med. and Surg. Journ., April, 1845. § Anatomical and Pathological Observations. Edinburgh, 1845. 8vo, No.x, p. 64.](https://iiif.wellcomecollection.org/image/b30379593_0009.jp2/full/800%2C/0/default.jpg)
