While the discovery of blood cells has a long and fascinating history, pinpointing the single discoverer of white blood cells (WBCs) requires nuance. Jan Swammerdam's 1658 observation of red blood cells under a microscope was a crucial early step, but white blood cells, being far less prevalent, required more advanced microscopy.
The key individuals in identifying white blood cells are William Addison and Gabrielle Andral. Although red blood cells (RBCs) were initially described in 1674 by Leeuwenhoek, it wasn't until over 160 years later, aided by improved microscopes, that Addison and Andral were able to distinguish and identify the less numerous white blood cells. This identification is reviewed by Hajdu in 2003.
Therefore, while the initial observation of blood cells dates back centuries, the specific identification of white blood cells is attributed to the advancements in microscopy and the work of William Addison and Gabrielle Andral.
