The Body Electric - Micro-ondes

38 The Body Electric
hobby. In a career spanning the second half of the eighteenth century,
Spallanzani discovered the reversal of plant transpiration between light
and darkness, and advanced our knowledge of digestion, volcanoes,
blood circulation, and the senses of bats, but his most important work
concerned regrowth. In twenty years of meticulous observation, he stud-
ied regeneration in worms, slugs, snails, salamanders, and tadpoles. He
set new standards for thoroughness, often dissecting the amputated parts
to make sure he'd removed them whole, then dissecting the replace-
ments a few months later to confirm that all the parts had been restored.
Spallanzani's most important contribution to science was his discovery
of the regenerative abilities of the salamander. It could replace its tail
and limbs, all at once if need be. A young one performed this feat for
Spallanzani six times in three months. He later found that the sala-
mander could also replace its jaw and the lenses of its eyes, and then
went on to establish two general rules of regeneration: Simple animals
can regenerate more fully than complex ones, or, in modern terms, the
ability to regenerate declines as one moves up the evolutionary scale.
(The salamander is the main exception.) In ontogenetic parallel, if a
specias can regenerate, younger individuals do it better than older ones.
THE SALAMANDER'S SKELETON - AS COMPLEX AS OURS