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Summary Article: Swammerdam, Jan (1637-1680)
from The Hutchinson Dictionary of Scientific Biography

Place: Netherlands

Subject: biography, biology

Dutch naturalist who investigated many aspects of biology but who is probably best known for his outstanding microscope observations, his detailed and accurate anatomical descriptions, and his studies of insects. He is considered by many to be a founder of both comparative anatomy and entomology.

Swammerdam was born in Amsterdam on 12 February 1637. He was the son of an apothecary whose hobby was a museum of curiosities, a hobby that stimulated the younger Swammerdam's interest in natural history, particularly in insects. He graduated with a medical degree from Leiden University in 1667 but never practised as a physician, preferring to pursue his interest in natural history. Subsequently his father, who wanted his son to become a priest, withdrew his financial support - despite which the younger Swammerdam continued his biological studies, although he suffered severe privations and became chronically ill, both physically and mentally. In 1673 Swammerdam came under the influence of the religious zealot Antoinette Bourignon and became increasingly embroiled in religious controversy until he died, only 43 years old, in Amsterdam on 15 February 1680.

Swammerdam made many important contributions to biological knowledge but most of his studies were of insects. He accurately described and illustrated the life cycles and anatomies of many species, including bees, mayflies, and dragonflies. In mayflies and dragonflies the change from the last nymph stage to the winged adult is outwardly the most striking, but Swammerdam showed that rudimentary wings occur in the aquatic nymphs some time before the final moult. He also showed that caterpillars develop wings and adult-type legs shortly before pupating. From his observations of their metamorphic development Swammerdam classified insects into four major groups, three of which are still used in a modified form in modern insect classification. In addition, he disproved many false beliefs about insects - for example, that their bodies are structureless, fluid-filled cavities without fully formed internal organs.

Swammerdam also studied vertebrates, about which he provided a substantial body of new knowledge, most of which was correct. He showed that the lungs of newly born mammals sink in water when the lungs are taken from the animals before breathing has started but that lungs taken from young animals whose respiration has been established float. He also erroneously believed, however, that the movements of the chest in mammals are unrelated to inhalation and exhalation but are associated with transferring air from the lungs to the heart. Swammerdam demonstrated that muscles removed from a frog could be stimulated to contract and that when muscle (including heart muscle) contracts it does not increase in volume. Furthermore, he anticipated the discovery of the role of oxygen in respiration by postulating that air contained a volatile element that could pass from the lungs to the heart (contributing to the respiration operation of the heart) and then to the muscles, providing the energy for muscle contraction. Investigating the anatomy of the frog, he observed that the frog's egg passes through a stage when it consists of four joined globules (now known to be the second cleavage of the fertilized egg). He was also probably the first to discover red blood corpuscles when he observed oval particles in frog's blood in 1658.

In his work on human and mammalian anatomy, Swammerdam discovered valves in the lymphatic system; these valves are now called Swammerdam valves. He also investigated the human reproductive system and was one of the first to show that female mammals produce eggs, analogous to birds' eggs. In addition he perfected a technique for injecting dyes into dissected cadavers in order to display anatomical details.

Swammerdam's work - particularly his insect studies - had a profound impact on scientific thinking, although his manuscripts were not published in full until 1737, when Hermann Boerhaave published Biblia naturae/Bible of Nature, a two-volume Latin translation of Swammerdam's Dutch text that included illustrations engraved from Swammerdam's own drawings. The work is one of the finest collections of biological observations ever published and, even today, many of Swammerdam's illustrations remain unsurpassed.

© RM, 2018. All rights reserved.

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