258 jEssaijs. 



geography o£ the Nortli Island to a close, many such thoughts as the follow- 

 ing present themselves for consideration : — 



Is there a natural law affecting the dissemination of plants ? 



Is a climate or geognostic difference of greater value than a mere 

 geographical one ? 



Did cosmopolite genera or species proceed from a single germ or 

 centre ? and, if so, how did they reach the extreme outposts ? 



Did endemic genera and species proceed from a single germ or centre ? 

 and, if so, can that centre he found ? 



Plovf is it that of some insular genera {e.r/. Copros^nci) there are many 

 species and varieties ; while of others {e.g. Corynocarpus, Geniostoma, 

 Garpodetus) there is only one ? 



Were all such genera created simultaneously ? and the large genus with 

 all its species and varieties ? 



Are genera having many species older than those having only one, or 

 vice versa ? 



May not the several species and varieties of an insular or endemic 

 genus be validly considered as having originally sprung from one species or 

 plant ? 



Why are several species of the numerous-seeding and easily-distributed 

 natural order Compositse so comparatively scarce and very local ? e.g., several 

 species of the genus Celmisia; the new Zealand dciisies, BracJigcome sinclairi 

 and B. odorata; Gnaplialmm prostratum, and G-. colensoi ; Senecio gregii, 

 and S. perdicioides ; and Taraxacum dens-leonis ? Senecio perdicioides has 

 not been found by any botanist since Cook's visit. Senecio gregii, although 

 producing its fine flov/ers by hundreds, is very local, hitherto only met with 

 in one rocky spot. And the small indigenous Taraxacum dens-leonis is com- 

 paratively very scarce ; while the larger introduced plant is rapidly becom- 

 ing a perfect pest, growing, together with the English daisy, by hundreds 

 and thousands. 



Does New Zealand (with the islets lying north and south) possess a 

 peculiar botany of her own ? 



Is New Zealand the centre of this botanical region, at least as regards 

 New Zealand species found north and south of her ? 



How is the isolation of certain species to one peculiar plant, spot, or 

 locality (as stated in paragraph 14), to be accounted for ? This last thought 

 is never more strongly felfc than when on the tops of a secluded mountain 

 range, or in the depths of a deep untrodden glen, one or a feit} plants of any 

 species are found, but no more ; perhaps no more in the island ! or, at all 

 events, no more have been detected after several years of diligent research. 

 How is this to be accounted for, if all present species were created as they 



