Power, Sex, Suicide: Mitochondria and the Meaning of Life Read Online Free PDF Page A

were simply dissolving the evidence. Other stains were ambivalent, colouring mitochondria only transiently, for the mitochondria themselves rendered the stain colourless. Their rather ghostly appearance and disappearance was scarcely conducive to firm belief. Finally Carl Benda demonstrated, in 1897, that mitochondria do have a corporeal existence in cells. He defined them as ‘granules, rods, or filaments in the cytoplasm of nearly all cells … which are destroyed by acids or fat solvents.’ His term,
mitochondria
(pronounced ‘my-toe-con-dree-uh’), was derived from the Greek
mitos
, meaning thread, and
chondrin
, meaning small grain. Although his name alone stood the test of time, it was then but one among many. Mitochondria have revelled in more than thirty magnificently obscure names, including chondriosomes, chromidia, chondriokonts, eclectosomes, histomeres, microsomes, plastosomes, polioplasma, and vibrioden.
    While the real existence of mitochondria was at last ceded, their function remained unknown. Few ascribed to them the elementary life-building properties claimed by Altmann; a more circumscribed role was sought. Some considered mitochondria to be the centre of protein or fat synthesis; others thought they were the residence of genes. In fact, the ghostly disappearance of mitochondrial stains finally gave the game away: the stains were rendered colourless because they had been
oxidized
by the mitochondria—a process analogous to the oxidation of food in cell respiration. Accordingly, in 1912, B. F. Kingbury proposed that mitochondria might be the respiratory centres of the cell. His suggestion was demonstrated to be correct only in 1949, when Eugene Kennedy and Albert Lehninger showed that the respiratory enzymes were indeed located in the mitochondria.
    Though Altmann’s ideas about bioblasts fell into disrepute, a number of other researchers also argued that mitochondria were independent entities related to bacteria,
symbionts
that lived in the cell for mutual advantage. A symbiont is a partner in a symbiosis, a relationship in which both partners benefit in some way from the presence of the other. The classic example is the Egyptian plover, which picks the teeth of Nile crocodiles, providing dental hygiene for the crocodile while gaining an easy lunch for itself. Similar mutual relationships can exist among cells such as bacteria, which sometimes live inside larger cells as
endosymbionts
. In the first decades of the twentieth century, virtually all parts of the cell were considered as possible endosymbionts, perhaps modifiedby their mutual coexistence, including the nucleus, the mitochondria, the chloroplasts (responsible for photosynthesis in plants), and the centrioles (the cell bodies that organize the cytoskeleton). All these theories were based on appearance and behaviour, like movement and apparently autonomous division, and so could never be more than suggestive. What’s more, their protagonists were all too often divided by struggles over priority, by war and language, and rarely agreed among themselves. As the science historian Jan Sapp put it, in his fine book
Evolution by Association
: ‘Thus unfolds an ironic tale of the fierce individualism of many personalities who pointed to the creative power of associations in evolutionary change.’
    Matters came to a head after 1918, when the French scientist Paul Portier published his rhetorical masterpiece
Les Symbiotes
. He was nothing if not bold, claiming that: ‘All living beings, all animals from Amoeba to Man, all plants from Cryptogams to Dicotyledons are constituted by an association, the
emboîtement
of two different beings. Each living cell contains in its protoplasm formations, which histologists designate by the name of mitochondria. These organelles are, for me, nothing other than symbiotic bacteria, which I call symbiotes.’
    Portier’s work attracted high praise and harsh criticism in France, though it was largely ignored in the