Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: May 13, 2025
I know of no more solid and important contributions to biology in the past seven years than Haeckel's work on the Radiolaria, and the researches of his distinguished colleague Gegenbaur, in vertebrate anatomy; while in Haeckel's Generelle Morphologie there is all the force, suggestiveness, and, what I may term the systematizing power, of Oken, without his extravagance.
Professor Gegenbaur has lately endeavoured to explain this resemblance by the derivation of each limb from a primitive form of fin.
Hence some remote progenitor of the whole vertebrate kingdom appears to have been hermaphrodite or androgynous. This is the conclusion of Prof. Gegenbaur, one of the highest authorities in comparative anatomy: see 'Grundzuge der vergleich. Anat. 1870, s. 876.
It was Carl Gegenbaur again who solved the difficult problem of tracing the skeleton of the limbs of the Vertebrates to a common type. Few parts of the vertebrate body have undergone such infinitely varied modifications in regard to size, shape, and adaptation of structure as the limbs or extremities; yet we are in a position to reduce them all to the same hereditary standard.
The aquatic Protoleptus, as we may term the ancestor of Leptus, may have had such tubes as these, which acted like the swimming bladder of fishes for lightening the body, as suggested by Gegenbaur. It is known that the swimming bladder of fishes becomes developed into the lungs of air-breathing vertebrates and man himself. The next inquiry is as to the origin of the wings.
I know of no more solid and important contributions to biology in the past seven years than Haeckel's work on the "Radiolaria," and the researches of his distinguished colleague Gegenbaur, in vertebrate anatomy; while in Haeckel's "Generelle Morphologie" there is all the force, suggestiveness, and, what I may term the systematising power, of Oken, without his extravagance.
This primitive fin, which Gegenbaur first recognised, is attached to the vertebral column by a simple zone in the shape of a cartilaginous arch. It is also found in modified form in some of the actual sharks and pikes. Human skeleton. Skeleton of the giant gorilla. The little or fifth toe is developed from the lower end of the fin-rod.
Ceratodus is particularly interesting on account of the primitive build of its skeleton; the cartilaginous skeleton of its two pairs of fins, for instance, has still the original form of a bi-serial or feathered leaf, and was on that account described by Gegenbaur as a "primitive fin-skeleton." At the same time the gills also are developed as water-breathing organs in all these lung-fishes.
This modern view, which had the support of the greatest expert on the vertebrates, Carl Gegenbaur, can be harmonised with the older theory to an extent, in the sense that both formations, scales and hairs, were very closely connected originally. It is confirmed by the similar arrangement of the two cutaneous formations.
This fact sustains the view of Gegenbaur that at first the tracheæ formed two simple tubes in the body-cavity, and that the primary office of these tubes was for lightening the body, and that their function as respiratory tubes was a secondary one.
Word Of The Day
Others Looking