532 
“ means of dispersal,” enormous difficulties have accom 
panied the process. I am far from denying that such 
means may have proved successful, so far that the wafted 
seed may have germinated and even produced seed. What 
we have now to consider is the part which Natural Selec 
tion plays in the process of adaptation by which the new 
immigrant adapts itself to its new conditions. The 
process which would have to take place is thus described 
by Mr. Wallace :— 
“ The change may affect a great many (of the species) injuriously 
to such an extent as to require some change in their structure or 
habits to enable them to get on as well as before. Now ‘variation’ 
and the struggle for existence come into play. All the weaker and 
less perfectly organised individuals die out, and while those which 
vary in such a way as to bring them into more harmony with their 
new conditions constantly survive. If the change of conditions has 
been considerable, then, after a few centuries, or perhaps in a few 
generations, one or more new species will be almost sure to be 
formed.”—(.Island Life. p. 56.) 
All the objections which have been urged against adap 
tation by Natural Selection when some members of a 
species emigrate into a contiguous sphere or along a line 
of unbroken communication, would beset the organisms 
wafted to a considerable distance. But in one or two 
respects the difficulties would be enhanced considerably. 
In the first place, the members of a given species thus 
carried to a distant sphere would be very few. Obviously 
an individual animal, unless it were a pregnant female, 
could not found a colony. At the most only a very few 
would be deported in this fashion, and these few would 
probably be enfeebled by their compulsory voyage; and 
from this cause, or from the mere change of climate, might 
not be so fertile as to provide that output of life which 
Natural Selection requires.