The first time "tulip breaking virus" was described was in 1576 by Carolus Clusius, a Flemish professor of botany. He called it "rectification" because he believed that the color changes were the plant trying to purify or "rectify" itself. Clusius also noticed the harm done to the bulb by the virus, but did not know that a virus was causing it. In fact, it took until a decade after World War I for scientists to figure out that a plant virus was the culprit for the color changes. This was considered quite late because plant viruses themselves were known to scientists since 1897. 