-- BE SURE TO VISIT MY WEBSITE, BELOW: ----------------------------------------------------------- George Hammond, M.S. Physics Email: ghammond@mediaone.net Website: http://people.ne.mediaone.net/ghammond/index.html -----------------------------------------------------------
attached mail follows:
Mark G wrote:
> Mark A. Grobner, Ph.D. > Department of Biological Sciences > California State University, Stanislaus > Turlock, CA 95382
> I would like to see the "well known textbook" that would suggest that the > body axis is physically caused by the first three embryonic cleavages.
[Hammond] Well, since I don't want to move from the comfort of my living room chair, I will simply refer you to this URL:
http://www.ucalgary.ca/~browder/cell_fate.html
where you will find the following quote:
quote ======================================================= MOSAIC and REGULATIVE Embryos
The difference between mosaic and regulative embryos lies in the timing of when fate restrictions become apparent in the embryo.
In mosaic embryos, the blastomeres become restricted during the first few cleavages. Because cell fates are established early, they cannot compensate for blastomeres that are removed or destroyed. E.g. in tunicates, separated blastomeres from the two cell embryo will develop into half embryos.
In regulative embryos, this restriction occurs later, so regulative embryos can compensate for blastomeres that are removed in early development. ==========================end quote===========================
The two half embryos referred to above are mirror symmetric left-right half embryos well known in the literature on the subject (cf. Conklin, 1905 and many others) The "mosaic" eggs (cf. tunicates), are always of more primitive animals than the "regulative" eggs of say, frogs and humans, indicating that "regulation" is simply an evolutionary advance from the old mosaic eggs. Nevertheless, this only changes the point at which "totipotency" begins. In very primitive animals totipotency only exists in the egg and is lost at the first cleavage. In higher animals it can last through the first, 2nd or even 3rd cleavage. Obviously this is an evolutionary adaptation which makes he egg more survivable, but hardly affects it's geometrical properties. The above author only mentions the 2-cell stage producing symmetric (L-R) 1/2 embryos, but Conklin in 1905 showed that the 2nd cleavage does the same thing "dorso-ventrally" by separating the 4-cell stage in half dorso-ventrally and producing a "dorsal 1/2 embryo" and a "ventral 1/2 embryo" in various specimens. some researchers have even produced 4, 1/4 embryos, by fully separating the 4 cell stage. No doubt about it, as far as Physics is concerned, the first 3 cleavages of the egg are geometrically isomorphic to the 3 cartesian body axes of the zoological body plan. Same for botany by the way, i.e., plants as well as animals. In fact therefore, it holds true for "all living things". BTW, Physics is well aware of the spiteful and vicious heretical subterfuge perpetrated by Driesch and Speman against Roux by trying to cover up the historic implications of his initial discovery of this relation by playing the "totipotency" canard. Biology students are still hypnotized by it, but Physics is not. Eventually, Roux's discovery lead to a scientific proof of God (Hammond, 1994, 1997, see my website), and this was the kind of thing Roux intuitively suspected, and Speman and Driesch were trying to bury by all available means.
-- BE SURE TO VISIT MY WEBSITE, BELOW: ----------------------------------------------------------- George Hammond, M.S. Physics Email: ghammond@mediaone.net Website: http://people.ne.mediaone.net/ghammond/index.html -----------------------------------------------------------
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