Il6 ASPLENIUM EBENOIDES. SCOTT S SPLEENWORT. 



wiler does not mention the latter species, which probably also 

 grows near the Alabama location ; but the association need sng- 

 o-est hybridity no more than in the case of others also often found 

 associated. Again, those who have experimented with them, tell 

 us it is extremely difficult to produce hybrid ferns. When 

 germination of the spore takes place, a small green blade called 

 the prothallus is formed. On the surface of this litde cups appear, 

 which represent the different sexes in flowering plants, and the 

 fertilizing dust, or pollen, as we should say in flowering plants, is 

 ejected from the one class, and has to fall into the other. The 

 chances of the ferdle vesicle, or, as it is technically called, the 

 archegonium, receiving fertility from any other source than its 

 own prothallus, are found to be very slim indeed. As a means 

 to make it more probable, hybridists sow the spores of two 

 species in immense abundance thickly togedier, so that when the 

 prothallia develop they may be pushed up on edge, and in that 

 way the antherozoids or " pollen " be more likely to be thrown 

 into the receptive vesicles of the other species. One experi- 

 menter reports that of millions of plants so favorably raised for 

 hybridizadon, he yet never saw but two undoubted hybrids. With 

 this difficulty it is scarcely within the probabilities that a hybrid 

 between the Walking and the Ebony ferns should appear in so 

 many different and such widely separated locations. 



Exi'l.AiNATlONS OF THE PLATE. — I. Plant of natural size from Miss Tutwiler's location. 

 2. 3. Various enlarged sections of pinnules from different parts of the plant, — show! 

 variations in the venation. 



