522 A NATURALIST IN THE PACIFIC CHAP. 



The history of climate, the history of the continents and of the 

 oceans, the history of life itself, but only in the sense below defined, 

 all belong to that of a desiccating world, or rather of a planet once 

 sunless and enveloped in mist and cloud, that through the ages has 

 been drying up. Life's types were few and the sea prevailed, and 

 one climate reigned over the globe. With the diminution of the 

 aqueous envelopes the continents began to emerge, climates began 

 to individualise, and organisms commenced to differentiate, and 

 thus the process has run on through the past, ever from the general 

 to the special both in the organic and in the inorganic world. 



The same story of a world drying up is told by the marine 

 remains left stranded far up some mountain slope, or by the bird 

 akin to no other of its kind that Time has stranded on some island 

 in mid-Pacific. The bird generalised in type that once ranged the 

 globe is now represented over its original range by a hundred 

 different groups of descendants, confined each to its own locality. 

 Climate, once so uniform, now so diversified, has by restricting the 

 range of the bird favoured the process of differentiation, and the 

 plant dependent on the bird for its distribution has in its turn 

 responded to these changes. 



The role of the polymorphous species belongs alike to the plant 

 and to the bird. A species that covers the range of a genus 

 varies at first in every region and ultimately gives birth to new 

 species in some parts of its range. Then the wide-ranging species 

 disappears and the original area is divided up into a number of 

 smaller areas each with its own group of species. Each smaller 

 area breaks up again, and forms, yet more specialised, are pro- 

 duced ; and thus the process of subdivision of range and of differen- 

 tiation of form goes along until each island in an archipelago owns 

 its bird and each hill and valley has its separate plants. This is 

 not the path that Evolution takes, since beyond lies extinction 

 whether of plant or of bird. Such is the upshot of the process of 

 differentiation exhibited in the development of species and genera 

 in the Pacific Islands, or, indeed, in any oceanic groups. It can 

 never do more than produce a Dodo or a Kiwi, or amongst the 

 plants a Tree-Lobelia. 



Evolution here and elsewhere is a thing apart from species and 

 genera, which are but eddies on the surface of its stream. It is a 

 scheme of life introduced into a much conditioned world, and 

 adaptation in endless forms is the price it has had to pay. The 

 whole story of life on this earth is a story of a sacrifice, of an end 

 to be won, but of a price to be paid. Immortality is in the 



