THE FERN BULLETIN 



109 



waged over this subject. Such a question on its 

 face has little of interest for the student who may 

 wonder that a difference of opinion should matter un- 

 til he learns that its proper settlement throws much 

 light upon the origin of fern leaves in general. In 

 view of the facts that this form may be made to prove, 

 botanists insist that fertile fronds, no matter how they 

 may appear at present, existed first and that the sterile 

 fronds are all modifications of them. 



It is one thing, however, to claim that the obtusilo- 

 bata forms are produced from what were intended to 

 be fertile fronds and quite another to prove it. This 

 Prof. G. F. Atkinson essayed to do in the spring and 



PINNAE OF STRUTHIOPTERIS GERMANICA F. OBTUSILOBATA 



summer of 1894. Since it requires a certain amount 

 of plant-food to produce any kind of a sporophyll that 

 is incapable of making its own food, he reasoned that 

 cutting off the sterile fronds would oblige the plant to 

 turn the fertile fronds, already laid down, into food- 

 making organs. Accordingly he removed the fronds 

 from a colony of these ferns early in May and when 

 the new crop of leaves appeared these also were cut 

 off. A third cutting was made later and then, as ex- 

 pected, the obtusilobata forms began to appear. 

 Others who have since tried the experiment have 

 sometimes failed to be successful, but it is likely that 

 their failure is due to the neglect to remove the fronds 

 often enough. 



