Microscopical morphology of the animal body in health and disease / by C. Heitzmann. With 380 original engravings.
- Carl Heitzmann
- Date:
- 1883
Licence: Public Domain Mark
Credit: Microscopical morphology of the animal body in health and disease / by C. Heitzmann. With 380 original engravings. Source: Wellcome Collection.
Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.
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![dKXF.HM. I'uoi'i'.inii:s or i.ivi.\<i mmikh. it saiiu'. Jiiul the itiain form of ]tl•(»|».•^^^•lti(»^^ is always a division. Even in tlu' most lii^lily (Icvt'lopcd mammals the embryo orij^inally forms a i»art of the mother-body, and, after having grown, by internal «;('mniation or endogenons production, up to a certain size, separates from tlie vehicle, the womb, and represents a new individual. (See Fij,'. 1.) Kemak was the finst to draw attention to tiie three forms of propagation, but he was not aware of their being materially identical, though morphologically different, manifestations of one and the same process. There is a striking peculiarity a])()ut generation, viz.: the resemblance of the newly formed })ody to the prodiicing organ- isms, the parents. It is an easy matter to understand that both indi\dduals will ))e aUke in a case of simple diN'ision, because both formerly made one single body; but how shall we explain the remarkable fact that, in higher animals, the off'sjiring so closely resembles the progenitors, though <tnly vin-y minute parts of these—the ovum and the spermatozoids—contributed to give rise to a new individual ? The opinion ()f E. Hering, that organized matter is endowed universally with an unconscious memor}-, a function upon which depends, besides the capacity of imagination, of thinking, of habit, also nutrition and propagation, is not an available one. I therefore take into consideration only the three modern hy- potheses of Charles Darwin, Louis Elsberg, and Ernst Haeckel. Darwin promulgated in 1868 the Pro\dsional Hypothesis of Pangenesis, which consists essentially in the assumption that thi'ough all stages of development the li\nng cells or units of the body thi-ow off small granules, or gemmules, which accumulate to form the sexual elements; and all the cells of the body, there- fore, participate indirectly in the new formation of organisms. In 1872, Elsl)erg published his theory of the Regeneration or Pres- ervation of the Plastidules. He lays down the proposition that the germ of every living individual contains plastidules of all its ancestors ; so that these are liodily regenerated in their offspring, simply because bodily particles are preserved directly from gener- ation to generation. In 187.'3, Haeckel announced the h\i3othesis of the '' Perigenesis of the Plastidules,'' according to which, in opposition to the opinions of Darwin and Elsberg. no regeneration or preservation and transmission of plastidules takes place, but only a transmission of motion through inheritance. Among these theories, I confess that that of Elsberg seems](https://iiif.wellcomecollection.org/image/b21219163_0043.jp2/full/800%2C/0/default.jpg)
