Daily Archives: 5 April 2014

April 5, 1859 (a Tuesday)

Charles Darwin, aged 51

On this date, Charles Darwin sent his publishers the first three chapters of The Origin of Species, which became one of the most influential books ever published.

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April 5, 1802 (a Monday)

Illustration by Felix Dujardin

On this date, the French physiologist, morphologist, and taxonomist Félix Dujardin was born. Dujardin is primarily known for his work with microscopic animal life, and in 1834 proposed that a new group of one-celled organisms be called Rhizopoda (meaning “root-foot”). This name was later changed to protozoa. In 1835, he disproved Ehrenberg’s hypothesis that microorganisms have the same organs as the more complex animals.

Also in 1835, he was the first to describe protoplasm, the jellylike material in animal cells which he called sarcode (from the Greek word σάρξ, meaning “flesh”). [Hugo von Mohl is credited with introducing the name protoplasm for it in 1846.] This substance, now called cytoplasm, was later found in living plant cells. Although the term protoplasm is rarely used any more in a strictly scientific sense, many of the notions associated with the term have survived. Thus it is still accepted that all living organisms are made largely of the same classes of substances such as salts and organic molecules, that some of these are organized into structures large enough to be seen in the microscope, and that water almost always is by far the most abundant material.

Dujardin’s written works include Histoire naturelle des infusoires (1840), Manuel de l’observateur au microscope (1842), and Histoire naturelle des helminthes (1844).