CHAPTER IV. 
THE THEORY COMPARED WITH THE REALITY. 
“ Things ough’ to ha’ took most an oppersite turn, 
But The’ry is jes’ like a train on the rail, 
Thet, weather or no, puts her thru without fail, 
While Fac’s the ole stage thet gits sloughed in the ruts, 
An’ hez to allow for your darned efs an’ buts, 
An’ so, nut intendin’ no pers’nal reflections, 
They don’t—don’t nut alius, thet is,—make connections.” 
—Lowell. The Biglow Papers. 
“ On parlait un jour de son Histoire Naturelle devant Voltaire. 
Oh ! pas si naturelle, dit celui ci d’une façon mordante.”—Said of 
Supports Natural History. 
“ ... in vain, 
Opinions, those or these, 
Unaltered to retain 
The obstinate mind decrees ; 
Experience, like a sea, soaks all-effacing in.” 
—Matthew Arnold. 
We have now to consider how far the facts of nature 
correspond with the requirements of the theory of Natural 
Selection, so far as its distinctive feature is concerned ; 
namely, the power of Natural Selection to select. It is 
assumed that the tendency to increase in a geometrical 
ratio leads to an enormous output of life, which is suc 
ceeded by the discriminative destruction known as Natural 
Selection. It is assumed that the ordinary output of life, 
apart from enormous fertility, is succeeded by discrimina 
tive destruction. It is assumed that there is always a 
competition going on in nature between members of the 
same species and individuals of different species. These