[Various aspects of blood cells in the 19th century]

Although the erythrocytes are known since the 17th century, their quantification and their way of production could only be described in the 19th century. As the result of the first cytological and histological colorations at that time, the different types of leucocytes were discovered and the first clinico-cytological descriptions of leukemia and of ganglionic disturbances could be made. The platelets were also identified, the knowledge of their functions and of their pathological aspects, however, was still very fragmentary.