310 HOFMEISTER, ON 



upwards for some distance, and consequently enclose the 

 true apex of the stem, together with the bud which consists 

 of two leaves corresponding with the former in every 

 respect. Presl (' Tent, pterid,' suppl., p. 41) has modified 

 this view. He considers the fertile and the sterile frond as 

 only segments of one and the same leaf, the under segment 

 of which becomes fruitful, whilst the upper remains leaf- 

 like. Mettenius (' Farrne des botan. Gartens zu Leipzig,' 

 1856, p. 119) and Roper also quite lately (' Bot. Zeit./ 

 1859, p. 244) have arrived at the same opinion. Braun,* 

 on the other hand, asserts that " the cellular body from 

 which in Ophioglossum the leaves are produced cannot be a 

 special sheathing leaf, nor even of the nature of a stipule or 

 ligule, but it is a cellular body which surrounds the centre 

 of growth, and inside which the leaves are formed in suc- 

 cessive spirals, and there remain. Within this body each 

 leaf forms its own cell, which enlarges with the growth of 

 the leaf, and becomes gradually elevated in a conical form, 

 and ultimately pierced in a sheath-like manner. The fruc- 

 tification of Ophioglossum is axillary ; it is the only leaf 

 which comes to perfection from a bud in the axil of a sterile 

 leaf. .... Botrychium does not possess the enve- 

 loping cellular body, but on the other hand, in this genus, 

 the leaves form their own sheaths." I have, myself at- 

 tempted to show that the most striking feature sug- 

 gested by Braun exists also in Botrychium, for I assumed 

 that each of the contemporaneously developed pairs of 

 fronds originated in an entirely closed cavity, being the base 

 of the next older pair of fronds. According to this the 

 stem of Botrychium would be a sympodium of the basal 

 portions of successive yearly shoots. f Schacht also agreed 

 in this view when he asserted that Botrychium was repro- 

 duced only by adventitious buds.f 



These notions, however, are founded in an error, easily 

 accounted for by the want of transparency of the tissue. 

 This error consists in omitting to observe the very narrow 

 points of junction of the cavities of the pairs of fronds as 



* 'Flora, 5 1S39, p. 301. 

 t 'Vergl. Unters.,' p. 88. 

 ' ' t 'DiePflanzenzelle, 5 p. 304. 



