Synopsis of Canadian Ferns and Filicoid Flanfs, 105 



planet before it lias been seen, and the chemist can con- 

 struct formulse for organic compounds — members of homo- 

 logous series — in anticipation of their actual discover}^, so, 

 in like manner the pteridologist now studies the variations 

 of species by a comparative system, which enables him to 

 look for equivalent forms in the corresponding species of 

 different groups. Studies so pursued are calculated to 

 evolve more accurate and definite notions as to the real 

 nature of species, and the laws of divergence in form of 

 which they are capable. I would therefore earnestly invite 

 Canadian botanists to a more careful study of the varieties 

 of the Canadian ferns, after the manner of Moore and other 

 European leaders in this comparatively new path. The 

 elasticity, or proneness to variation, of the species in certain 

 groups of animals and plants has been somewhat rashly 

 used to account for the origin of species, by what is called 

 the process of variation. It seems to tell all the other way. 

 Innumerable as are the grotesque variations of ferns, in 

 forkings, and frillings, and tassellings, and abnormal vein- 

 ings, &c. (see the figures in Moore's works), we do not know 

 of a single species in which such peculiarities have become 

 permanent or general, that is specific^ so that the species 

 can be traced back to such an origin ; surely something of 

 the kind would have happened had all species originated by 

 a process of variation. 



Tahular View of the Distribution of Canadian Ferns and Allied 

 Plants over certain parts of the Northern Hemisphere.^ 



Name. 



I. 



II. 



III. 



IV. 



V. 



Canada. 



Northern 

 States, i 



Southern 

 States. 



Europe. 



Arctic 

 Circle. 





POLYPODIACE^, 













1. 



Poly podium vulgare, . . 



+ 



+ 



+ 



C.B. 



Eu. 



2. 



P. hexagonopterum, . 



+ 



+ 









3. 



P. Phegopteris, .... 



+ 



+ 





cVb. 



Eu, G. 



4. 





+ 



+ 





C.B. 



Eu.Am.G. 



* In the above Table, the doubtful species are included ; but all reference 

 to varieties is omitted. 



NEW SERIES, VOL. XIX. NO. J. JANUARY 1864. O 



