258 Essays. 
geography of the North 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 geognostie 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 be found ? 
How is it that of some insular genera (e.g. Coprosma) there are many 
species and varieties; while of others (e.g. Corynocarpus, Geniostoma; 
Carpodetus) there is only one? i 
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 versá ? 
May not the several species and varieties of an insular or endemie 
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 Composite 80 comparatively scarce and very local? e.g., several 
species of the genus Celmisia; the new Zealand daisies, Brachycome sinclairi 
and B. odorata; Gnaphalium prostratum, and G. colensoi; Senecio greyii, 
and S. perdicioides; and Taraxacum dens-leonis ? Senecio perdicioides has 
not been found by any botanist since Cook's visit. Senecio greyii, although 
producing its fine flowers 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 accountedfor? This last thought 
is never more strongly felt than when on the tops of a secluded mountain 
range, or in the depths of a deep untrodden glen, one or a- Jew plants of any 
Species are found, but no more; perhaps ho 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 
