13 
representing the mean dimensions of the species, but this was by no 
means the case. Often the central point was not all crowded with 
dots, but they were grouped with rough uniformity for a considerable 
distance on each side of the centre, with a few isolated at greater 
distances representing the extremes of variation. Hence a species 
could usually be divided into two portions, with a considerable 
number of specimens in each showing divergence from the mean 
condition—the very ‘simultaneous variation’ which Mr. Romanes 
regards as ‘a very large assumption.’”—(The Fortnightly Review, 
vol. xl., N.S., ft. 30Q.) 
Variations are thus represented as divergent, i.e., radiating 
in all directions ; as forming a cluster around a central line ; 
and as forming two clusters at some little distance from 
the central line. 
We find a similar discrepancy in the statements as to 
the strictness or the laxity of the selection which takes 
place in nature. 
Mr. Wallace says :— 
“ Selection is constantly .... eliminating all that fall below 
the best working standard, and preserving only those that are fully 
up to it.”—(.Darwinism. ft. 413.) 
But elsewhere he speaks of— 
“A struggle for existence, in which the weakest and least perfectly 
organised must always succumb.”—(Contributions to the theory of 
Natural Selection, ft. 33.) 
He also says :— 
“Nature does not so much select special varieties as exterminate 
the most unfavourable ones.”—(Wallace’s Letter in Darwin’s Life. 
Hi., ft. 46, note.) 
Mr. Darwin says :— 
“We must suppose each new state of the instrument (the human 
eye) to be multiplied by the million : each to be preserved until a 
better one is produced, and then the old ones to be all destroyed.” 
—(Origin of Sftecies. ft. 146.) 
On the other hand, the principle of a lax selection is 
asserted in the following passages by Mr. Darwin.