86 OPHIOGLOSSACEAE [ch. 



O. moluccamim described by Mettenius and by himself; and that of O. pendidum^ on which 

 he has added largely to the earlier observations of Lang. The first type is characterised 

 by early formation of the root and late development of the axis and leaf; in the second the 

 leaf and root only appear to be developed at first ; in the third roots only ; and he states 

 that in both O. nioluccanum and peiiduhit)i the definitive sporophyte is "formed as an 

 adventitious bud upon the root of the embryo sporophyte." The bud is described as 

 endogenous, and the illustrations bear this out. With so experienced an observer as 

 Campbell there is no reason to doubt the facts. It appears to be a question rather of 

 interpretation {Eiisp. Ferns, p. 40, Figs. 22-24). There can be no question of the near 

 affinity of the various species of Ophioglossum. It would appear therefore more probable 

 that the embryogeny should follow one plan subject to modifications, than that the plans 

 should be so distinct in the dififerent species as that one should form its main shoot by 

 "first intention," while in other species it should be by adventitious origin of so important 

 a part. An attempt to find another interpretation of the facts seems preferable to the 

 acceptance of Campbell's conclusion. 



The species described appear to form a sequence of specialisation in mycorhizic 

 nutrition, the precocious root being an essential feature in it. O. vjilgatutn shows this in 

 a less specialised form : its late-developed shoot is hidden away and deeply covered in by 

 the overlapping sheaths (Fig. 387). In O. 7noluccamim 2.xv^ pendulum the development of 

 the stem-apex is still later. If it were covered over by embryonic tissue, as it is seen to be 

 in O. vulgatum, the channel described by Bruchmann {c, Fig. 387) might well be 

 indistinguishable, but the originally organised apex be still there, and ready to awake to 

 activity, as it is shown by Campbell to do {Eusp. Ferns, pp. 41, 42, Figs. 24, 25). The apex 

 would have been lying dormant, and not be formed de novo. There is a good precedent for 

 such complete closure of a similar channel above an apex in the tubers of Phylloglossiim : 

 here it has been shown how completely that channel may be closed {Phil. Trans. ll, 1885, 

 PI. 71, Fig. i), and the steps leading to it have been depicted (PI. 72, Figs. 28-33). A like 

 obliteration of the channel described by Bruchmann for O. vulgatuni would give the con- 

 ditions described by Campbell for O. moluccanuni axyd pendulum. These embryos would 

 then take their place not as the primitive basis for wide morphological arguments, but as 

 highly specialised modifications of embryology in accordance with a peculiarly specialised 

 nutrition. 



Mycorhiza. 

 Fungal infection is widespread in the family, and it affects both the 

 generations. The prothalH of all three genera are saprophytic symbionts, 

 and the existence of chlorophyll in them is exceptional. There is some 

 exactness in the segregation of the infected areas, the hyphae being present 

 in the basal regions of the prothalli, but they are excluded from the upper and 

 more particularly from the superficial parts, in which the apical growth is 

 located, and the sexual organs are borne (Figs. 375, 378, 379). This distribu- 

 tion has its analogies with what is seen in symbiotic Orchids. The distribution 

 of mycorhiza in the sporophyte has been fully stated in The Origin of a Land 

 Flora (p. 477), where the literature is quoted up to that date. In the Ophio- 

 glossaceae it appears to be inconstant: it is seen in the adult plant of 

 O. vulgatuni, pendulum and siinplex, and in the latter it is certainly associated 

 with marked morphological peculiarities. In Hebninthostachys it is present 



