Discovery of red blood cells

The first observation and description of red blood cells is credited by the Wikipedia article on Jan Swammerdam to the Dutch microscopist himself, who in 1658 was the first to observe and describe them, using the microscope that he was one of the first to apply to dissection. The Wikipedia article on Marcello Malpighi adds that Malpighi was one of the earliest people to observe red blood cells under a microscope, after Swammerdam. The observation belongs to the early microscopy of blood in the middle of the seventeenth century, when the instrument first showed that blood is not a uniform fluid.