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Swammerdam, Jan

muscle frog contracts preparation

(1637–80) Dutch naturalist and microscopist; a pioneer of modern entomology and discoverer of red blood cells.

Swammerdam’s father, an apothecary, had a ‘museum of curiosities’ and the boy helped with this and became a keen insect collector. He studied medicine at Leiden (with as a fellow student) and graduated in 1667 but he never practised medicine, despite his father’s protests and financial pressure. When only 21, he discovered the red blood cells of the frog. Also from the frog, he introduced the nerve–muscle preparation into physiology. This consists of a leg muscle with its nerve, dissected from a recently killed frog; when the nerve is stimulated, the muscle contracts. By immersing the preparation in water in a container with a narrow outlet, Swammerdam was able to show that when the muscle contracts, there is no change in its volume, contrary to earlier belief.

For the second half of his fairly short life he was a victim of mental illness, but this did not stop his skilful pioneer work on insects and their microanatomy. His minute dissections of the mayfly, bee, tadpole and snail were not surpassed until, in the 18th-c, the compound microscope was much improved. His work showed the complexity of small animals (eg the compound eye, sting and mouth of the bee). Much of this work was not found until 50 years after his death, when it was published as The Bible of Nature (1737).

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