Sunbeams, Cucumbers, and Purple Bacteria: the Discovery of Photosynthesis Revisited

Abstract

In November 1987, Robert Hill, of Cambridge (England) was awarded Copley Medal of Royal Society in recognition of his pioneering research on process of photosynthesis. During late 1 930s, Hill [2] demonstrated light-dependent production of oxygen (gas) by chloroplasts, tiny green bodies present within cells of plant leaves. These experiments not only localized actual site of photosynthetic machinery of plant cells but also proved that water is source of oxygen that plants produce. In fact, oxygen production by chloroplasts is a primary source of Earth's atmospheric oxygen, required for existence of all animal life. Hill's experiments were a major milestone in more than 200 years of research aimed at explaining fundamental physiology of plant life. In 1970, Hill wrote an article [3] on The growth of our knowledge of photosynthesis from ancient to modern times. After discussing concepts of plant nutrition held by early Greek philosophers, Hill reviews the beginnings of modern experiment in seventeenth and eighteenth centuries, but says little of brilliant investigations of Rev. Dr. Stephen Hales (1677-1761).