124 Mr. A. H. Church. On the Occurrence of [Apr. 26, 



Vines, 2nd Ed., 1882), we have Bquisetum, Ophioglossum, Salvinia, 

 and Marsilea, on one side of Lycopodium, with Psilotum and then 

 Selaginella on the other — omitting, however, several families, includ- 

 ing the true ferns. The results were negative. 



100 parts oF ash 

 contained 



Percentage of ash 



in dry plant. A1 2 3 . Si0 2 . 



PJquisetum maximum .... 20*02 none 62*95 



Ophioglossum vulgatum . . 8*25 none 5*32 



*Salvinia natans 16*82 1'86 671 



* Marsilea quadrifoliata .. . 11*66 0*54 0'88 



The alumina found in Salvinia was proba hly due to the presence 

 of traces of soil from which it was found impossible to free this 

 floating water-plant. Both the Salvinia and the Marsilea were grown 

 in the lily house, Kew, and I have to thank the Director of the Royal 

 Gardens for the material which I submitted to analysis. 



The genus Psilotum has been mentioned as botanically near to 

 Jjijcopodium; it contains but two species, one of which was examined 

 for alumina with a negative result. 



100 parts of ash 

 contained 



Percentage of ash ( A ^ 



in dry plant. A1 2 3 . SiOo. 



Psilotum triquetrum ... . 5*06 trace? 3*77 



After Psilotum follows Phylloglossum, of which one species only has 

 been recognised ; this plant is too rare and too minute to be available 

 for analysis ; the same remark applies to the allied species Tmesipteris 

 tannensis. Selaginella comes next, and then Isoetes. An analysis of 

 at least one of the species of this last-named genus is still a deside- 

 ratum. 



I will now revert, still following the classification of Sachs, to tbe 

 true ferns. In none of the British species have I been able to detect 

 more than traces of alumina. But among the exotic Cyatheaceae 

 which Sachs places above the Polypodiaceaa, there seems to be a 

 notable exception. Last year Mr. W. F. Howlett, of Pahiatua, 

 Wellington, New Zealand, forwarded to Mr. Thiselton Dyer some 

 specimens of the ashes of a tree-fern. He wrote, under date 22nd 

 February : " The other day I found a half -burnt Punga, or tree-fern. 

 The ashes were pure white, very tenacious, and retained the structure 

 of the wood. They were obviously not in any way contaminated 

 with accidental impurities, nor had they been rained upon. 

 I wrote to a chemical student who said the ashes were chiefly alumina. 

 This is very new to me. Alumina is generally thought an accident, 

 here it cannot be so. I do not know the species of tree-fern." 



