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THE AMERICAN NATURALIST 



[Vol. XLI 



this being very marked in the larger species of Botrychium. The 

 two segments of the sporophyll may be almost entirely separate, 

 e. g., Ophioglossum bergianum, Botrychium ternatum, or the fertile 

 segment may be apparently an outgrowth of the base of the sterile 

 segment or from above its base. 



The earlier views of the morphologic value of the fertile leaf 

 segment were strongly influenced by the prevailing theory that 

 the fertile portion was a secondary development of originally 

 sterile leaf tissue, and therefore must be homologized with some 

 portion of the sterile leaf. The belief more generally current 

 at present that the fertile structures of the sporophyll are older 

 than the sterile ones, inclines toward a different interpretation 

 of the real nature of the fertile segment. 



Bower (Studies in the ^Morphology of Spore-producing Mem- 

 bers, II, Ophioglossacese. London, 1896) has given a very com- 

 plete account of the different theories that have been advanced 

 to explain the morphology of the fertile spike in the Ophioglos- 

 sacete, and we shall merely give here a brief summary of the more 

 important of these. ]\Iettenius (Fame des Bot. Garten zu Ixip- 

 zig. 1856, p. 119) regarded the two parts of the leaf as of equal 

 importance, but gives no data as to their method of origin, — 

 whether by the equal branching of a common primordium or 

 otherwise. Later writers, e. Holle (Bot. Zeit. 1875, p. 271) 

 and Goebel (Schenk's Handbuch, vol. 3, p. Ill) consider the 

 fertile spike as the equivalent of the fertile pinnse of such a fern 

 as Aneimia. The former considers the single median spike to 

 be the result of the coalescence of two lateral pinnie; the latter 

 as a single pinna which arises in a median position. 



Bower himself has made the most complete study of the develop- 

 ment of the spore-bearing parts of the Ophioglossacete that has 

 ever been made. He concludes that the spike of Ophioglossum 

 is morphologically equivalent to the single sporangium of Lycopo- 

 dium. In this view he has the support of Strasburger (Bot. 

 Zeit., 1873) and Celakovsky (Pringsheim's Jahrb., 1SS4, vol. 14). 

 Bower has, however, more recently described a most remarkable 

 species of Ophioglossum (Ann. of Bot. 18, p. 205, 1904) (). .simp/r.r 

 Ridley, which makes possible another interpretation of the nature 

 of the spike, i. c, that it is a terminal and not a lateral organ. 

 The writer (Mosses & Ferns, 2d edit., p. 600) in view of the dis- 



