422 = The Limits of Organic Evolution. [May, 
is probable that in many respects it will be a death blow to its 
evolution. Man is rapidly causing the extinction of almost all 
land animals, at least the larger ones. As the frontiers of civili- 
zation are being extended further and further into the uninhabited 
regions, he is driving out of existence all of the larger animals 
and many of the smaller ones. We have ,only to look ahead a 
comparatively short time to see the extinction of all land animals 
except such as man may preserve for his own use. To what ex- 
tent this may apply to other animals, to insects, marine animals, 
etc., is not clear. But in the highest group of animals, the verte- 
brates, it is pretty clear that man is eventually to bring about not 
only the end of advance, but also the practical extermination of 
all animals except such as he especially preserves. 
With all of these considerations together it seems perfectly plain 
that we must look upon the evolution of the animal kingdom as 
definitely limited and approaching an end. The tendency of spe- 
cialization to advance to extreme limits, the impossibility of the 
further adaptation of these extremes to new conditions, the sig- 
nificant fact that no new forms of importance have arisen during 
all the later geological ages, the great influence of man in causing 
extermination of all sorts of animals, all these point to the same 
end. Just as evolution began in time, so it will end in time, and 
we must look upon the animal kingdom as progressing toward a 
limit. When this limit is reached, either there will follow a grad- 
ual extinction through a diminution of vital power, or if this be 
not the result, a stationary condition will ensue in which such 
animals as man has left in existence will remain unmodified until 
the progress of physical changes makes this world no longer 
habitable. 
