3S8 
DISPERSAL OF DOMINANT RACES. 
external adaptation to modified liabits or environment without tlie 
marked structural advance that wouhl probably ensue were the asso- 
ciated and competitive organisms themselves more highly developed; 
this is demonstrated by the fact that in Australia and other I’emote 
regions of the globe occupied by the lowlier forms of life and which 
have not yet been invaded by the most advanced races, although a 
rich variety of species are developed, there has been little or no material 
advance in structure. 
Tlie place of origin of the mollusca and other terrestrial organisms 
has, however, by most writers been located in the remote, inaccessible 
and comparatively nnknown regions of Central Asia, a belief based 
mainly upon a mathematical calculation fixing a central point in the 
range of species, the presence there of a maximum number of species 
of certain genera belonging to more generalized forms of life than 
tliose of Eurojie, the discovery of more numerous fossil remains or 
in earlier strata than the beds of Europe containing similar relics 
and the ab.sence of any evidence that the forms now confined to Asia 
have ever inhabited the extreme North or South of Europe. 
I'nless, however, a group be a dominant one, its original home is 
not necessarily indicated by the aggregation at the present day of 
its constituent species, as the true evolutionary area of a group when 
no longer dominant may not retain even a single representative of the 
genus or family, its species having been expelled or overcome by the 
stronger forms which have arisen and suj)planted them, while the 
geological record is confessedly too incomplete and fragmentary to 
overthrow conclusions based upon the solid facts of structure and 
geographical distribution by the merely negative evidence it may 
otter, evidence also peculiarly liable to continual correction and 
alteration by the results of future research and discovery; therefore, 
so far from agreeing with the theory of the eastern origin of the 
various forms of life or the reasoning by which it is supported, I 
regard the Central Asiatic i)lateau and Asia generally in a lesser degree 
as an asylum where those weaker or less adaptable forms of life still 
exist, which have migrated or been expelled from the regions more 
immediately adjacent to the active evolutionary centre by the intense 
Itressure and competition of the highly organised and more adaptable 
forms, which will inevitably in process of time invade their present 
refuge, only in turn to be disp(jssessed by the still more advanced 
forms which will assuredly follow. 
