192 PHYSIOGNOMY OF PLANTS. 



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 phsenogamous 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 arid Hornemann's Catalogues 

 the relative numbers of Eilices are, for Lapland -^V, for 

 Iceland y^-, and for Greenland T 1 2 . 



Such, according to the present state of our knowledge, are 

 the natural laws manifested in the distribution of the pleasing 

 form of Perns. But it would seem as if in the family of 

 Eerns, 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-Sumiriski, who happily unites the gift of microscopic 

 examination with distinguished artistic talent, has discovered 

 in the prothallium of ferns an organisation by which fructifi- 

 cation 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 

 Na'geli. The fertilisation is supposed to take place not by 

 pollen tubes but by the moveable ciliated spiral threads. 

 (Suminski zur Entwickelungs-geschichte der Earrnkrauter, 

 1 848, S. 10-14.) According to this view, Eerns, as Ehrenberg 

 expresses it (Monatl. Berichte der Akad. zu Berlin, Januar 

 1848, S. 20), would be produced by a microscopic fertilisa- 

 tion taking place on the prothallium as a receptacle ; and 

 throughout the whole remainder of their often arborescent 



