William Hewson's studies of red blood corpuscles and the evolving concept of a cell membrane

The botanist Carl Nägeli is generally considered to have laid the basis for the cell membrane concept by his 1855 study of the osmotic properties of plant cells. It is shown here that William Hewson in 1773 presented cogent experimental evidence for the concept of a cell membrane in red blood corpuscles. Although his work was largely confirmed in subsequent studies, and a cell membrane became an attribute of the cell in T. Schwann's cell theory, the idea of a cell membrane was rejected by anatomists in 1861 essentially on theoretical grounds, and plant physiologists did not mention Hewson's pioneering endeavour. As a consequence, Hewson's work has been ignored to this day. A broad cell membrane concept then had to await the ingenious work of Overton, started in 1895. The possible reasons for these lapses in scientific recognition are analyzed.