In 1711, R.A.F de Réaumur gave an account of Fucus in which noted the two types of external openings in the thallus: the non-sexual cryptostromata (sterile surface cavities) and the conceptacles (fertile cavities, immersed but with a surface opening) containing the sexual organs, which he thought were female flowers. With a lens he was able to see the oogonoa (the female sex organs) and the antheridia (the male sex organs) within the conceptacles, but he interpreted these as seeds (Morton, 1981 p. 245).[1] Johann Hedwig (1730–1799) provided further evidence of the sexual process in algae, and figured conjugation in Spirogyra Hedwig in 1797. He also illustrated Chara (Charales) and identified the antheridia and oogonia as male and female sexual organs (Morton, 1981 p. 323 & 357).[1]