Photo of Cornelius Barnardus Van Niel

Cornelius Barnardus Van Niel

  • National Medal of Science
  • Biological Sciences

For his fundamental investigations of the comparative biochemistry of microorganisms, for his studies of the basic mechanisms of photosynthesis, and for his excellence as a teacher of many scientists.

Growing up, Cornelius Bernardus Van Niel – “Kees” to his friends – accepted the explanation all children hear from their parents: “Because I said so.”

An event in high school, however, forced the future microbiologist to shun this reasoning forever.

At a family friend’s agricultural estate – while observing experiments testing the effectiveness of soil treatment on crop production – Van Niel was surprised to learn that “one could raise a question and obtain a more or less definitive answer to it as a result of an experiment,” he wrote in a 1967 memoir.

Thus, a scientist was born.

In 1931, while studying bacteria, Van Niel became the first person to understand the chemistry of photosynthesis, the process by which plants convert light from the sun into energy.

Among his key discoveries, Van Niel determined that oxygen released by plants during the process comes from the splitting of water molecules, not from the carbon dioxide as previously believed.