Meckel proceeds to exemplify the thesis, that the lower forms of animals represent stages in the course of the development of the higher, with a large series of illustrations.
Meckel, "Anatomie des Gehirns der Vogel," in Meckel's Archiv f.
267-269) - first put forth in Meckel's Deutsches Archiv fiir die Physiologie (vi.
Riester and Sanson in an appendix to the sixth volume of the French translation of Meckel's Anatomy, 1829); 2.
Meckel, 3 on the other hand, while equally accepting Brongniart's classification, retained the term Amphibia in its earlier Linnaean sense; and his example has been generally followed by German writers, as, for instance, by H.
The greatest of all investigators of animal structure in the 19th century was Johann Miller (1801-1858), the successor in Germany of the anatomists Rathke (1793-1860) and Meckel (1781-1833).
Thus the recapitulation law, which had been built up independently from the observations and speculations on vertebrates by Lorenz Ofen (1779-1851), Johann Friedrich Meckel (1781-1833), St Hilaire, Karl Ernst von Baer (1;92-1876) and others, and had been applied (1842-1843) by Karl Vogt (1817-1895) and Agassiz, in their respective fields of observation, to comparison of individual stages with the adults of the same group in preceding geological periods, furnished the key to the determination of the ancestry of the invertebrates generally.
Meckel (1781-1833) he edited the Archiv fur Anatomie and Physiologie.
Mck, Meckel's cartilage.
In a remarkable essay 3 Meckel remarks: ' ` There is no good physiologist who has not been struck by the observation that the original form of all organisms is one and the 1 " 11 s'agit donc de prouver que la serie qui constitute l'echelle animale reside essentiellement dans la distribution des masses principales qui la composent et non dans celle des especes ni meme touj ours dans celle des genres."
After comparing the salamanders and the perenni-branchiate Urodela with the tadpoles and the frogs, and enunciating the law that the more highly any animal is organized the more quickly does it pass through the lower stages, Meckel goes on to say: " From these lowest Vertebrata to the highest, and to the highest forms among these, the comparison between the embryonic conditions of the higher animals and the adult states of the lower can be more completely and thoroughly instituted than if the survey is extended to the Invertebrata, inasmuch as the latter are in many respects constructed upon an altogether too dissimilar type; indeed they often differ from one another far more than the lowest vertebrate does from the highest mammal; yet the following pages will show that the comparison may be also extended to them with interest.
If Meckel's proposition is so far qualified, that the comparison of adult with embryonic forms is restricted within the limits of one type of organization; and if it is further recollected, that the resemblance between the permanent lower form and the embryonic stage of a higher form is not special but general, it is in entire accordance with modern embryology; although there is no branch of biology which has grown so largely, and improved its methods so much since Meckel's time, as this.
Meckel's diverticulum-A congenital abnormality of the digestive tract consisting of a small pouch off the wall of the small bowel that was not reabsorbed before birth.
A Meckel's diverticulum increases the risk that a foreign object in the digestive tract will get trapped or stuck in the small intestine and cause problems.
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