15 



Meeting of November 24, 1925 



The meeting was held at Schermerhorn Hall, Columi)ia Uni- 

 versity, under the joint auspices of the Torrey Botanical Club 

 and the Institute of Arts and Sciences of Columbia University. 

 President Richards introduced the speaker of the evening. Dr. 

 F. O. Bower, Regius Professor, University of Glasgow. An 

 abstract of the lecture, prepared by Professor Bower, on the 

 Natural Classification of Ferns, follows: 



A natural classification should be based on the widest possible 

 foundation of fact: theoretically it should accord with all the 

 known facts relating to the organisms classified. If the classi- 

 fication be correctly carried out it should represent accurately 

 their relations by descent. This is the ideal end: but under 

 present conditions it is Utopian, and in practice we must be 

 content with as wide a basis of fact as possible, and a result 

 which at least shall not violate, but rather represent phyletic 

 relations. 



Of all the classes of plants none appears to lend itself so readily 

 to phyletic treatment as the Filicales. The reasons for this are: 

 (i) that they are represented today by a very large number of 

 genera and species of wide geographic distribution; (ii) that they 

 have many well marked and relatively stable characters; and 

 (iii) that they have a long and consecutive fossil history, back to 

 Paleozoic time. 



The attempt has been made to widen the criteria used in their 

 comparison with a view to phyletic grouping, and twelve criteria 

 have been adopted, though doubtless the number may be added 

 to by later writers: 



i) External form of the shoot 



2) Leaf-architecture and venation 



3) Initial constitution 



4) The vascular system 

 Sporophyte (5) Dermal appendages 



6) The position and structure of the sorus 



7) Indusial protections 

 The characters of the sporangium 

 The spore-output per sporangium 



( 

 Gametophyte ( 



( 



The form of the prothallus 

 The sexual organs 

 Embryology 



