Miescher discovered DNA in 1869 whilst studying pus-ridden bandages that were being sent to the laboratory by the local clinic. At this time the lab was working on the chemistry of body fluids, particularly blood. To that end the young physician was studying lymphocytes, though these were hard to obtain. So he was isolating leukocytes (which were thought to be derived from lymphocytes) from pus. Once these cells were prepared he managed to isolate pure nuclei, and from there he extracted a high phosphorus-containing substance, and described it.
The man who discovered DNA did not know that it was the hereditary material and he also did not call it DNA. He referred to it as 'nuclein' because it had come from the nucleus. He expected it to be present in organs such as the liver and kidney, and he also believed it to be an acid. He wrote to his uncle, "With experiments using other tissues, it seems probable to me that a whole family of such slightly varying phosphorous-containing substances will appear, as a group of nucleons, equivalent to the proteins." Thus he had discovered nucleic acid, but it was two years before his work was published because his laboratory head wanted to replicate the results.
