Bakee, F.R.S. : Geography of British Plants. 



133 



the north of England, we have no such records for the very interesting 

 counties of Westmoreland, Cumberland, and Lancashire. I attempted 

 long ago to collect notes about the Lake district, and if no one else 

 enters the field, shall feel inclined to publish them, incomplete as they 

 are ; and whilst speaking of this matter, I cannot leave it without 

 expressing a hope that some day we may see in print, the full material 

 which Mr Warren has gathered together for Cheshire, which would be 

 specially acceptable, because we have no recent flora for any western 

 county. 



Broadly speaking, the external conditions which affect the dispersion 

 of species may be classified under three heads. By these I mean, first, 

 how a species is influenced by climate ; secondly, how it is influenced 

 by soil ; and thirdly, how its dispersion at the present time is affected 

 by its past history, and 'the changes that have taken place in the 

 conformation of sea and land in past times. A fourth influence, to 

 estimate which at its full value is one of the great lessons we have 

 learnt from Mr. Darwin, is brought about by the large extent to which 

 plants depend on insects for their fertilisation. This has been fully 

 dealt with of late years by many investigators. Speaking of the other 

 three factors, I should say that, for Britain as a whole, the vertical and 

 horizontal range of each species has been so fully registered that the 

 climatic range of the British plants is fully worked out, but that under 

 the two other heads there are several fields of work that want further 

 following out. 



In tracing out the pedigree of species, a great deal still remains to 

 be done in gathering together, sifting, and testing the evidence derived 

 from palseontology. As an example of a valuable recent contribution 

 to our knowledge in this department, I may cite the memoir on the 

 Ferns of the British Eocene Strata, recently published in the Transac- 

 tions of the Palaeontographical Society, by Mr. Starkie Gardiner and 

 Baron von Ettingshausen. It would appear already in the eocene 

 period, that the present sub-orders, and many of the present genera of 

 ferns, were already differentiated, and there is no evidence of the 

 existence then of any type of subordinal value that is not in existence 

 now. There are at the present time eight distinct sub-orders of Filices, 

 each distinguished by a characteristic type of sporange. Out of the 

 forty-three British ferns which exist at the present day, thirty-seven 

 species belong to Polypodiacefe, three to Hynienophyllacese, two to 

 Ophioglossaceae, and one to OsmunclaceEe. Four sub-orders, Gleiche- 

 niace^, Cyatheacese, Marattiaceag, and SchizEcaceas, are at the present 

 day not represented in Britain, nor, in fact, anywhere in Europe. In the 



