THE FERNS 137 



attracts the attention of the botanist. The Leptosporan- 

 giates, on the other hand, occur everywhere in the most 

 astonishing profusion and variety, often constituting 

 the most conspicuous feature of the flora of certain 

 districts, especially in the higher mountains. 



The conclusion is irresistible that in the Leptospo- 

 rangiatse we have to do with a comparatively modern 

 type of plants, eminently adapted to existing conditions 

 and competing successfully with the highly specialized 

 flowering plants. The small number, both of species 

 and individuals, among the Eusporangiates points to the 

 opposite condition in their case. They show every evi- 

 dence of plants that are being worsted in the struggle 

 for existence by their more specialized competitors. 



A study of the anatomy of the sporophyte as well as 

 the gametophyte confirms this view. We find that the 

 gametophyte in the Eusporangiates approaches that of 

 the liverworts much more closely both in its structure 

 and long duration, and the reproductive organs are 

 much more like the liverwort type than are those of 

 the leptosporangiate ferns. The embryo also remains 

 much longer connected with the gametophyte, and the 

 differentiation of its members does not take place until 

 a later period. Finally, the sporophyte has simpler 

 tissues, and the sporangium is of a less specialized 

 type, approximating the conditions found in the highest 

 liverworts. In short, the theory of the Eusporangiatae 

 being primitive and presumably an older type than the 

 Leptosporangiatse is borne out by every detail of their 

 structure. 



That the Leptosporangiates have been derived from 

 the Eusporangiates is indicated by the number of 



