On February 28, 1953, American molecular biologist James D. Watson and English biophysicist Francis Crick announced to friends that they succeeded to determine the chemical structure of DNA.
On April 2, 1647, the German naturalist and scientific illustrator Maria Sibylla Merian was born. Even though she is not very well known for her achievements, she made significant contributions to entomology through the observation and documentation of the metamorphosis of the butterfly.