REVIEWS—ON THE ORIGIN OF SPECIES. 371 
of plan with the same distinctness of type as in existing Nature; and 
that in no part of the world can we glean from them any examples 
even approaching to a transitional series of forms, in the sense de- 
manded by the theory. But leaving this subject for awhile, let us 
examine the theory itself, as modified and set forth in Mr. Darwin’s 
Essay, a little more in detail. We will take in succession the more 
prominent chapters of the book, and attempt respectively, a brief 
analysis of their contents. 
In his first chapter, the author discusses the variations to which 
Species give rise under domestication. He considers more especially 
and in great detail, the various breeds of the domestic pigeon. He 
shews, and every one must be familiar with this fact, the extraordinary 
differences in external aspect, mode of flight, etc., exhibited by many 
of these. So great is this diversity of character, that Mr. Darwin 
thinks an Ornithologist would not hesitate to class most of these breeds 
as distinct species, if he met with them for the first time, and were led 
to suppose them wild birds; nay, that he would even feel warranted 
in placing them under several genera. And yet, Mr. Darwin regards 
all our known breeds as undoubted descendants of the rock pigeon, the 
Columba livia. The strongest fact, perhaps, in favour of this view, is 
the production from time to time in various breeds, of the normal 
colours of the supposed parent-type. The question however, is by no 
means proved. If these pigeons have all sprung from Columba livia, 
should there not be occasionally a more striking reversion to the char- 
acters of the original type? Are we moreover authorised to conclude 
from any direct evidence, that a pair of rock pigeons could ever pro- 
duce the numerous varieties that we now possess? Mr. Darwin shews 
us that a certain amount of variation does constantly occur amongst 
pigeons generally, and hence he assumes by inference that in course of 
time, the variation being accumulative, so to say, we might obtain the 
breeds we now possess. It seems, however, as legitimate an inference, 
notwithstanding Mr. Darwin’s able advocacy of the contrary view,, 
that various sub-species or varieties of the pigeon were originally 
created ; just as we believe the leading varieties of the dog and horse. 
have sprung from originally-created varieties. We have certainly ne. 
authority to assume that the greyhound and the mastiff were not 
originally created as such, although capable of breeding together, and 
producing fertile offsprmg. We can produce varieties now, because 
we have varieties from which to produce them ; but if we had to, breed 
