19 



would be more natural, but this deserves a study of a wide array of 

 forms. 



4. The unfortunate and illogical treatment of Polypodium. A 

 few of the more striking groups like Dipteris, Drynaria, and Ar- 

 thropteris have been separated, but this is only a beginning. Of 

 our American species, P. polypodioides, the least divergent of all, 

 has been placed in the genus Lepicystis, while the others are all re- 

 tained in Polypodium. And the same characters that elsewhere 

 have been regarded as of importance, namely, vegetative charac- 

 ters, have been utterly disregarded. Surely our Polypodium vul- 

 gare, aureum, phyllitidis, and Swartzii represent four distinct gen- 

 era if Diplazium is to be separated from Asplenium, Polystichum 

 from Dryopteris, and Camptosorus from Scolopendrium, or either 

 from Asplenium, where Linnaeus placed them. 



Venation, belogning to a fundamental portion of the growth of 

 the sporophyte, must for the future be regarded as of first import- 

 ance in the taxonomy of ferns, and when the system of the future is 

 finally attained, we believe it will be found that the systems of Presl 

 and John Smith will approximate very closely to that ideal. This 

 will involve a greater regard for the fibre-vascular system as repre- 

 sented in venation, and growth characters based on a study of root- 

 stock and caudex, than we have presented in the system under re- 

 view. 



Columbia University, June, 1900. 



EXPERIMENTS IN HYBRIDIZING FERNS. 



BY MARGARET SLOSSON. 



Various arguments have been advanced both for and against 

 the probable occurrence of hybridity among ferns in nature, but I 

 shall not here enter into the "pros and cons." There is now no 

 doubt that fern hybridization is possible ; it has been brought about 

 artificially. To give the most convincing instance, Mr. E. J. Lowe 

 has succeeded in crossing Ceterach officinarum and Scolopendrium 

 vulgare, two ferns belonging not only to different species, but to 

 different genera. 



The next step is to ascertain whether fern-hybridization occurs 

 in nature ; if so, to what extent, and which are the hybrid ferns. 



