1 10 Prof. G. Gulliver on the Leaf-cells of Hymenopliyllum. 



very recent book on British Ferns by Messrs. Sowerby and 

 Johnson. Sir Wilham Jackson Hooker, in his ' Genera Filicum * 

 (1842), in like manner merely gives a figure, by Mr. Bauer, of 

 the cells of the same species, better than that in the ' English 

 Botany,^ but still with the intercellular passages too large. 

 Four species oiHymenophyllum are figured and described in the 

 * Century of Ferns ' (1854), by the same author ; but no infor- 

 mation is given about the cells ; nor does any appear in the 

 works either of Mr. Francis, Mr. Newman, Professor Babington, 

 or Mr. Bentham. Even the great books of Mr. Moore and Mr. 

 Lowe contain no notice of any variety or difierence in these leaf- 

 cells. Hence it might be inferred that they are all alike, or not 

 worth notice in the several species of this interesting genus. 

 But it will presently be shown how probable it is that the form 

 and size of the leaf-cells may afford good distinctive characters, 

 even in the absence of the fruit and of well-grown leaves ; and 

 perhaps Sir W. J. Hooker had seen the difference as regards 

 size merely, since of H. Wilsoni, in the fourth edition of the 

 ' British Flora,^ he remarks, " more rigid and with larger reticu- 

 lations than the last.'^ 



Of these plants Mr. Newman says, " In retaining the two as 

 distinct species I merely bow to the opinion of better botanists 

 than myself/' while in the second edition of 'English Botany' 

 it is stated, " Were not the fructification so remarkably different, 

 H. Wilsoni could scarcely be considered a distinct species ;" and 

 lastly, Mr. Bentham describes this as a variety merely of H. Tun- 

 bridgense. But Sir W. J. Hooker, Professor Babington, and 

 other high authorities seem to have no doubt that these plants 

 are really different species ; and this view is supported by the 

 observation of Mr. F. Clowes of Windermere, that " all the fronds 

 of H. Tunhridgense are annual, while those of H. Wilsoni go on 

 growing from year to year." 



My own obsei-vations, having been confined to two tufts of 

 the plants, are only presented as a suggestion for further com- 

 parative examination of their leaf-cells, when, should the differ- 

 ence prove to be regular and constant, it is to be hoped that the 

 shape and size of these cells will in future form part of the 

 descriptive characters of both the British and exotic species. 



H. Tunhridgense. — Leaf-cells round, or nearly so, with an 



average diameter of jyy of an inch. 

 H. Wilsoni. — Leaf-cells oval, with an average long diameter 



of 3^^Q and short diameter of -^\j, the mean of the two 



diameters being ^y^ of an inch. 



Thus, besides their much larger size, the form of the cells is 

 distinctly oval in H. Wilsoni ; and the diagnostics of the two 



