Wilhelm Roux

Roux killed one of the first two cleavage cells of a frog's egg with a hot needle and saw the survivor often grow into a half-embryo²³. Later authors read this as support for organ-forming regions in the egg¹. Others disputed that reading, and Roux rejected the preformationist label⁵.

Born: 9 June 1850
Died: 15 September 1924
Country: Duchy of Saxe-Weimar-Eisenach
Field: biologist, zoologist, university teacher
In the library: 0 works, named in 12 passages elsewhere
Facts from: Wikidata · Wikipedia

The half-embryo experiment

Roux plunged a hot needle into one of the first two blastomeres of the frog's egg. As a rule the surviving cell developed into only a half-embryo, with one half of the body missing³⁴. Verworn reported that the missing half could later appear by what Roux called post-generation². Loeb called the result classical. He noted that O. Schultze, who turned the egg upside down at the two-cell stage, obtained two whole embryos. Loeb explained this by a flow of protoplasm that Roux's setup had avoided⁴.

Preformation and its critics

Verworn placed Roux with Weismann among the defenders of organ-forming germ regions in the egg¹. Roux protested against being called a preformationist. Verworn kept his judgment and quoted Roux's own words so readers could decide⁵. Child said Roux proposed qualitative nuclear division to account for orderly differentiation, and Weismann adopted it. Experiments by Driesch and many others later led Roux to abandon the hypothesis⁶. Child also said Roux gave regulation a physicochemical basis but framed it in a preformistic theory of heredity⁷.

Regeneration by rearrangement

Morgan cited Roux on regeneration of pieces of hydra. A piece takes no food while it regenerates, so Roux argued that the cells already present must rearrange. Roux compared this to the post-generation of a sea-urchin blastula piece. He concluded that regeneration may proceed largely by rearrangement and re-differentiation of cells, with little or no proliferation⁸.

SourcesEach quotation was checked word for word against the passage it opens.

Roux ('95) and Weismann ('92, 2) are the latest defenders of this view, which affirms that different areas are present in the eggVerworn, M., 1899 · General Physiology: An Outline of the Science of Life · open at passage 1350
in which he observed that after artificial destruction of one of the first two cleavage-cells, from the other at first only halfembryos developedVerworn, M., 1899 · General Physiology: An Outline of the Science of Life · open at passage 1350
Roux carried out his experiment by plunging a hot needle into one of the first two blastomeres, so that it is injured to such an extentMorgan, T. H., 1901 · Regeneration · open at passage 556
Roux destroyed one of the two first cleavage cells of a frog's egg with a hot needle and found that as a rule the surviving cell developed into only a half-embryo.Loeb, J., 1916 · The Organism as a Whole, from a Physicochemical Viewpoint · open at passage 230
Since Roux has protested against being reckoned among the preformationists, where he has been placed not only by myself, but by manyVerworn, M., 1899 · General Physiology: An Outline of the Science of Life · open at passage 1354
Roux advanced the hypothesis of qualitative nuclear division as a basis for the orderly and harmonious differentiation of parts and Weismann adopted the idea.Child, C. M., 1924 · Physiological Foundations of Behavior · open at passage 74
According to Roux regulation has a physicochemical basis and is dependent upon physiological correlation, but his interpretation is in terms of a preformistic theory of heredityChild, C. M., 1924 · Physiological Foundations of Behavior · open at passage 552
regeneration may be brought about entirely, or very largely, through the rearrangement and re-differentiation of cells without any, or with very little, proliferation taking place.Morgan, T. H., 1901 · Regeneration · open at passage 49