0/60 REVIEWS—ON THE ORIGIN OF SPECIES. 
producing, contrary to an earlier belief, geological changes of the 
greatest magnitude. But the two cases have no true parallelism. 
One who had never seen the sea, or had never studied its effects, 
might naturally be inclined to look with ineredulity on statements of 
its. wasting powers, and of the results asserted to arise from these. 
But if he were to reside for a certain time on a sea-coast, where this 
wasting action were going on, and thus witnessed how, bit by bits 
the destruction of the coast took place, he could not shut his eyes to 
the fact, that, however slight the annual waste, this must amount in 
a given number of years, to such or sucha quantity. In like manner, 
one residing near an estuary in which rock-sediments were constantly 
under process of deposition, would be forced to acknowledge by what 
he saw daily or annually going on, that in course of time (other 
conditions not interfering) a delta of greater or less extent must 
necessarily arise. But to make the two cases parallel, we should 
have to assume that these natural processes would produce, not their 
obvious and natural results, but some altogether unexpected issue. 
Natural selection as maintained by Mr. Darwin, is undoubtedly a 
modifying power or principle of recognised action; and no one can 
read the section of his book which refers to that subject, without 
deriving profit and instruction from the perusal. But when the 
author attempts to establish the sufficiency of this power to effect 
generic changes, stronger arguments are certainly required, than any 
he has yet been able to bring forward. 
After some additional remarks of an interesting and original 
character, on the laws influencing variation, but which our compara- 
tively limited space compels us to pass over, we arrive at a distinct 
portion of the work, in which the author, having stated his views. in 
detail, and advanced facts in support of the theory which these 
-embody, takes up the so-called difficulties of this theory, or the 
questions which oppose themselves to its reception. Some of these 
have been already touched upon, and others must have suggested 
themselves to the reader, but we have forborne to consider them 
collectively until reaching the present part of the work, in which 
they are boldly brought forward and combated by the author himself. 
Mr. Darwin enunciates them as follows: 
“Lone before having arrived at this part of my work, a crowd of difficulties 
will have occurred to the reader, Sume of them are so grave that tc this day I 
ean never reflect on them without being staggered; but, to the best of my judg- 
