JTW's Evolutionary Origins - Author: Bibel, Jan D.
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Elie Metchnikoff - Thread of the Amoeboid Cells
"Metchnikoffs initial focus on the mobile cells of the starfish in Messina was not a chance event. He had been fascinated with their origin and activity for years, first meeting the amoeboid cells of metazoa while a student in investigations of spong-es and flatworms, creatures lacking a digestive cavity. He had observed that those nutrients that enter the mouth are engulfed by amoeboid cells, many of which wander through intercellular channels to spread the now digested foodstuff about the organism. In his examination of the metamorphosis of starfish larvae to adults, he had noted the ingestion and absorption of cellular debris of disappearing organs by the amoeboid cells. Metchnikoff also had found such cells with similar activity in superficial wounds of medusae. Amoeboid cells had not even escaped attention in his embryological pursuits. Haeckel's gastraea, the hypothetical first metazoan whose endoderm was supposed to have developed from the invagination of a blastula-shape assemblage of single-cell organisms, had presented a serious challenge. Metchnikoff agreed that metazoa had arisen from such a colony, but he envisioned that, through successive replications, there had occurred a selection of cells that favored movement into the hollow of the sphere to digest their food. Over time the colony became an organism by differentiation into an outer layer of cells, which provided protection and locomotion, and an inner group of wandering, flagellum-free digestive cells, which eventually joined into a solid inner layer. Until his death, Metchnikoff held onto the belief that phagocytosis, even in the formation of antibodies, was by evolution rooted in digestion."(Bibel, 1982)
Metchnikoff's Legacy
"It may even be that at long last the figure of Metchnikoff is no longer quite the domineering contemporary that he has always seemed until recently. Mind you, he still dominates, but one senses that the field is at last in active movement. Soon he will be far enough behind so as to be waved at respectfully, instead of, as usually happens, our finding him greeting us as we come up the road."(Lewis Thomas, 1969 quoted in Bibel, 1982)
Lewis Thomas wrote this in 1969, Bibel quoted Thomas's sentiments in 1982. Much has changed over this time but it is my opinion that we will still be encountering Elie Metchnikoff's presence on the road ahead for a long time to come.
(JTW)
- Bibel, Jan D.
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