Cell Sorting by Sponges
This photograph shows a painting of Wilson, with Nelson Hairston and Calhoun Bond in the foreground.
Oil painting of Albert Harris by his father Kenneth Harris,
NOTE: Wilson did not believe that cells rearrange according to cell type; that idea was later proposed by Julian Huxley, based on his own observations of dissociated sponge cells.
Wilson believed that dissociated sponge cells switch from one differentiated state to another, depending on cell locations.
Does position control differentiation? (As Wilson argued against) (Cells at the surface of aggregates switch cell type to become skin, etc.) Or is re-positioning of cells controlled by which differentiated cell type they are? (Skin cells move from the interior back to the surface, re-forming skin.)
Later Wilson published papers arguing that sponges reform by differentiation of previously undifferentiated "archeocytes" (analogous to stem cells). (This is analogous to Columbus arguing that he had reached China, not discovered new continents.)
Wilson tried mixing dissociated cells from sponges of different species, trying to make super-sponges that might be economically useful. It didn't work. Cells of different sponge species separated from each other.
This is in contrast to what happens if you dissociate and mix cells from salamanders and frogs, or from birds and mammals. See notes on Cell Sorting, October 6th
A sponge that has ingested fluorescent beads
Sponges crawling on the wall of an aquarium, over the course of several days.
Lots more sponge pictures for anyone who needs more.
Bond, Calhoun, and Albert K. Harris (1988). Locomotion of sponges and its physical mechanism. J. Exp. Zool. 246: 271-284.
Bond, Calhoun (1992). Continuous cell movements rearrange anatomical structures in intact sponges. J. Exp. Zool. 263: 284-302.