The earliest observations as to the propagation of lichens were made by Malpighi[525] who recorded the presence of soredia on the lichen plant and noted their function as reproductive bodies. He was followed after a considerable interval by Tournefort[526] who placed lichens in a class apart owing to the form of the fruit: “This fruit,” he writes, “is a species of bason or cup which seems to take the place of seeds in these kinds of plants.” He figures _Ramalina fraxinea_ and _Physcia ciliaris_, both well fruited specimens, and he represents the “minute dust” contained in the fruits as subrotund in form. The spores of _Physcia ciliaris_ are of a large size and dark in colour and were undoubtedly seen by Tournefort. Morison[527], in his _History of Oxford Plants_, published very shortly after, dismissed Tournefort’s “seeds” as being too minute to be of any practical interest. Micheli[528], with truer scientific insight, made the fruiting organs the subject of special study. He decided that the apothecia were floral receptacles, _receptacula florum_, and that the spores were the “flowers” of the lichen. He has figured them in a vertical series in situ, in a section of the disc of _Solorina_ saccata[529] and also in a species of _Pertusaria_[529], in both of which plants the ascospores are unusually large. He adds that he had not so far seen the “semina.” Micheli’s views were not shared by his immediate successors. Dillenius[530] scarcely believed that the spores could be “flowers” and, in any case, he concluded that they were too minute to be of any real significance in the life of the plant. Linnaeus[531], and after him Necker[532], Scopoli[533] and others describe the apothecia as the male, the soredia as the female organs of lichens. These old time botanists worked with very low powers of magnification, and easily went astray in the interpretation of imperfectly seen phenomena. Koelreuter[534], a Professor of Natural History in Carlsruhe, who published a work on _The discovered Secret of Cryptogams_, next hazarded the opinion that the seeds of lichens originated from the substance of the pith, and that the overlying cortical layer supplied the fertilizing sap. Hoffmann[535] devoted a great deal of attention to lichen fructification and he also thought that fertilization must take place within the tissue of the lichens. He regarded the soredia as the true seeds, while allowing that a second series of seeds might be contained in the scutellae (apothecia).