104 ON THE LATEST FORM OF THE DEVELOPMENT THEORY. 
Civilized man also has successfully waged war against many ferocious or noxious. 
animals, and probably exterminated some of them. But the appearance of a rival or 
hostile race is not the only cause of such diminution or extinction. A change in the 
physical features of a given district may partially or entirely depopulate it, without the - 
necessary introduction of any new-comers. The drying up or filling up of a lake is 
necessarily fatal to all its aquatic tribes. The gradual submergence of an island or 
a continent must exterminate, sooner or later, all the native Species which were peculiar 
toit. And at the utmost, the failure of any Condition of Existence, whatever may be 
its character, only leaves vacant ground for the future introduction or creation of new 
forms of life, without tending in the slightest degree to bring such new forms into 
existence. | | | 
9. Natural Selection, also, as already remarked, has nothing to do with the origin of 
Species, and, in its abstract form, is only the statement of a truism. Of course, when 
two or more Species crowd each other, the more prolific or the more vigorous, other 
things being equal, is more likely to gain possession of the disputed ground, and thus 
to diminish the numbers of the other, or oblige it to migrate, or, in rare cases, to kill 
it out altogether. But this last supposition is a conceivable rather than a probable 
result. All observation goes to show, that every Species retains a very persistent hold 
upon life, however feeble may be the tenure of existence for its individual members. 
Its numbers may be materially diminished ; it may be forced to shift its ground, and 
to suffer in consequence some slight change in its habits; (Mr. Darwin himself tells 
us of upland geese and of woodpeckers where there are no trees;) it may be driven 
into holes and corners; but somehow it still survives. Utter extinction of a Species 
is one of the rarest of all events; not half a dozen cases can be enumerated which are 
_ known to have taken place since man's residence upon the earth. And these, surely, 
are a very insufficient basis on which to found a theory embracing all forms of life. 
Yet man is the greatest exterminator the world has ever known. His physical powers, 
coupled with the use of reason by which they are multiplied a thousand-fold, enables 
him to wage internecine war with comparative ease against nearly every race that 
molests him. Only the insect tribes, through their immense numbers and their little- 
ness, can successfully defy him ; and these not always. In Ais Struggle for. Life, all 
other creatures, animal or vegetable, must retreat or perish. Yet how few has he 
rooted out altogether! But the Development Theory requires us to believe that this 
process of extinction, guided by Natural Selection, has been repeated wellnigh to in-: 
finity. Not only all the races which are now found only in their stone coffins, bot 
countless others, — “the interminable number of intermediate forms which must have 
