The plates were drawn by the celebrated zoologist and artist Ernst Haeckel (1834-1919), who promoted Darwinian theory in Germany, much as Thomas Huxley did in England.  Though trained as a medical doctor, Ernst Haeckel, was drawn to zoology when he began studying Radiolaria on a visit to Messina.  Before long, he was reading Darwin's Origin of the Species (1859), going on to receive a doctorate in zoology from Jena (1861).  He remained at that university for the rest of his teaching life, first as lecturer, later as full professor. As an artist and an expert on marine invertebrates, Haeckel was commissioned to illustrate the radiolarians encountered during the Challenger expedition.