In the search for the male organs of the fern attention was naturally directed to the neighbourhood of the sorus, and the stomata, indusia and glandular appendages were in turn mistaken by various observers for the anthers. The "limit" was reached by Griffith who, as is stated at page 190, conjectured that the Anabena filaments which accompany the megasporangia of Azolla were no other than the male organs of that plant. Schleiden spoke of these researches with the utmost scorn. "For my part I am surprised that no one has yet insisted upon the presence of the organs of sense, as eyes and ears in plants, since they are possessed by animals. Such an assumption would not be a bit more absurd than the mania of insisting upon having anthers in the Cryptogams, simply because they are found in the Phanerogams." All these ill-grounded hypotheses were swept away in 1844 when Nägeli discovered antheridia containing spermatozoids on the "cotyledon" or pro-embryo of the fern--the prothallus we call it now. Nägeli at once recognised their essential agreement with the antheridia already known in the Bryophytes and compared the spermatozoids with the corresponding structures in animals. But as he overlooked the existence of the archegonia, or rather by some lapse mistook them for stages in the development of the antheridia, it is not surprising that he was at a loss to understand the significance of his discovery, and that he should have commented on his dilemma in the following terms. "Seeing that the female organs (spores) arise on the frond at a much later stage of development, and long after the pro-embryo has died away, the function of the spermatozoids is far from evident."