- [Footnote: frequency increase again rapidly; that is to say, the number
of species of ferns decreases much more slowly than does the number of species of phænogamous plants. At the same time, the luxuriance, abundance, and mass of individuals in each species augments the illusive impression of absolute numbers. According to Wahlenberg's and Hornemann's Catalogues the relative numbers of Filices are, for Lapland 1/25, for Iceland 1/18, and for Greenland 1/12.
Such, according to the present state of our knowledge, are the natural laws manifested in the distribution of the pleasing form of Ferns. But it would seem as if in the family of Ferns, which has so long been regarded as a cryptogamic family, we had quite recently arrived on the traces of another natural law, a morphological one of propagation. Count Leszczyc-Suminski, who happily unites the gift of microscopic examination with distinguished artistic talent, has discovered in the prothallium of ferns an organisation by which fructification is effected. He distinguishes a bisexual arrangement in the ovule-like cell on the middle of the theca, and in the ciliated antheridia or spiral threads before examined by Nägeli. The fertilisation is supposed to take place not by pollen tubes but by the moveable ciliated spiral threads. (Suminski zur Entwickelungs-geschichte der Farrnkräuter, 1848, S. 10-14.) According to this view, Ferns, as Ehrenberg expresses it (Monatl. Berichte der Akad. zu Berlin, Januar 1848, S. 20), would be produced by a microscopic fertilisation taking place on the prothallium as a receptacle; and throughout the whole remainder of their often arborescent]*
