148 SIR WILLIAM HOOKER 



species : and natural habit is often a safer guide than minute 

 microscopic characters." Thus we see that in his method 

 convenience of diagnosis is put before the use of important 

 structural characters. I have recently found reason to uphold 

 the opinion of Mettenius on this point, and to confirm Plagio- 

 gyria as a substantive genus. 



Similarly, the genera LopJwsoria and Metaxya will have to 

 be detached from Alsophila: Prantl removed Microlepia from 

 Davallia into his new family of the Dennstaedtiinae, where they 

 are related with Patania {Dennstaedtid), which Hooker had 

 merged into Dicksonia. Goebel also has detached Hecistopteris 

 which Hooker had placed in Gymnogramme, and has placed it 

 with the Vittarieae. These are all examples of the way in 

 which further study is tending to reverse the excessive merging 

 of genera, which Hooker carried out in the interest of diagnostic 

 convenience. 



The general conclusion which we draw from contemplating 

 Sir William Hooker's work on the systematic treatment of ferns 

 is that it was carried out consistently to the end under the 

 influence of the current belief in the Constancy of Species. The 

 methods were not phylogenetic, as they have since become 

 under the influence of evolutionary belief The problem seems 

 to have been to depict and describe with the utmost accuracy 

 the multitudinous representatives of the Filicales, and to arrange 

 them so that with the least possible difficulty and loss of time 

 any given specimen could be located and named. But the 

 result is not to dispose them in any genetic order. Even the 

 arrangement of the larger genera according to the complexity of 

 branching of the leaves appears as a method of convenience 

 rather than of genesis, and subsequent inquiry is tending to show 

 that so far as such series really exist, they will require to be 

 read in converse. Goebel, in his paper on Hecistopteris, remarks 

 that " the systematic grouping of the Leptosporangiate Ferns, as 

 it is at present, e.g. in the Synopsis Filicum, is artificial throughout ; 

 it is adequate for the diagnosis of Ferns, but it does not give 

 any satisfactory conclusion as to the affinity of the several 

 forms." He proceeds to say that "a thorough investigation, 

 taking into account the general characters of form of both the 



