42 A CONTRIBUTION TO, ETC. 



Such being the case, therefore, I am led to a conclusion rather 

 different from that which is arrived at by the eminent writers to 

 whom I have alluded ; and I cannot express my own ideas on the 

 subject in terms more sound and philosophical than those enun- 

 ciated in Dr. Mueller's elegant preface to his " Vegetation of the 

 Chatham Islands." After stating his conviction that " the num- 

 ber of species has been vastly overrated," he adds, " the writer 

 has never been led to assume that limitation of species is hope- 

 less, or that an uninterrupted chain of gradations absolutely con- 

 nects the forms of the living creation. Analytical dissections, 

 counting by hundreds of thousands, instituted as well on living 

 plants in the field as on the material accumulated in his museum, 

 have never left such impressions on his mind ; but, on the con- 

 trary, convinced him of the great truth that the Supreme Power 

 to which the universe owes its existence called purposely forth 

 those wonderful and specifically ever- unalterable structures of 

 symmetry and perfection structures in which a transit to other 

 species would destroy the beautiful harmouy of their organization, 

 and would annihilate their power to perform those functions 

 specially allotted to each in this great world from the morn of 

 creation to the end of this epoch. But, be it understood, nature 

 only created species, occasionally, but not permanently oblit- 

 erated in their characters by hybridism. Genera and orders are 

 merely the strongholds around which we arbitrarily array them 

 to facilitate generalization, to ease the search, and to aid the 

 memory. Hence the limitation of these must depend entirely on 

 the individual view of the observer, and therefore be ever vacil- 

 lating ; but this should not finally be the fate of the species." I 

 have deemed it advisable to refer to the variations of species on 

 the present occasion, because the plants which I am about to no- 

 tice belong to a family that is somewhat protean in its character, 

 and in which species appear to have been unnecessarily increased. 

 It has been the fault of naturalists sometimes to regard every 

 aberration from the usual type as indicative of specific difference, 

 without duly considering, as Dr. Mueller observes, " the various 

 climatic or geologic circumstances to which a species can pos- 

 sibly be subject." In treating of ferns, this caution seems very 

 important, for the same species sometimes assumes different 

 forms and shapes, not merely from the influence of soil and cli- 



