REVIEWS—ON THE ORIGIN OF SPECIES. 375 
conditions. The first slight change, in an accumulative series of 
changes produced inaplantoranimal,can scarcely be effected otherwise 
than through the direct or indirect influence of external causes. In 
his introduction, Mr. Darwin alludes to the “ Vestiges of Creation,” 
but seeks apparently to mask the mutual affinities of the two 
works, by assuming, for the earlier one, a theory which certainly 
does not in any way fairly represent its views. He states, for 
example :— 
“Tt is preposterous to attribute to mer2 external conditions, the structure, for 
instance, of the woodpecker, with its feet, tail, beak, and tongue, so admirably 
adapted to catch insects under the bark of trees. In the ease of the misseltoe, 
which draws its nourishment from certain trees, which has seeds that must be 
transported by certain birds, and which has flowers with separate sexes absolutely 
requiring the agency of certain insects to bring pollen from one flower to the 
other ; it is equally preposterous to account for the structure of this parasite, with 
its relations to several distinct organic beings, by the effects of external conditions, 
or of habit, or of the volition of the plant itself. 
The author of the ‘ Vestiges of Creation’ would, I presume, say that, after a 
certain number of generations, some bird had given birth to a woodpecker, and 
some plant to the missletoe, and that these had been produced perfect as we now 
see them.” 
Now the “ Vestiges’? theory, really supposes nothing of the kind; 
but, and in so far at least in accordance with Mr. Darwin’s view, 
that one form is capable of originating another, by a slow and 
accumulative process of development. The author of “the Vestiges ” 
does not assume, for example, that a bird of an absolutely different 
kind ever gave birth to a woodpecker “ perfect as we now see 16; 
but that this latter type originated from an older one, by slight, 
gradual, and long-continued modifications of beak, claws, &c.,—the 
process giving rise to a complete series of intermediate forms. The 
two theories are thus essentially alike; although the works them- 
selves stand widely apart. Whilst the one contents itself with 
broad assumptions, the other seeks to afford proofs of its statements, 
and honestly brings forward and discusses points apparently hostile 
to its views. All the proofs it is able to collect, however, are, as we 
have already attempted to shew, totally inadequate to affect the 
main question. But—explains Mr. Darwin—although the changes 
recorded are confessedly slight, they are sufficient to show what 
would be accomplished, if greater time were called into play ; and, 
in illustration of this, he refers to the agency of present causes in 
