REY. JOHN GERARD, F.L.S., ON SPECIES AND THEIR ORIGIN. 129 
soldiers clad in the same uniform and going through the same 
evolutions, necessarily implies a controlling force directing things 
according to a detinite system. So true is this that if along a 
road we travelled we should find at every twenty yards, or 
other regular interval, merely a couple of stones laid one upon 
the other, or three arranged as an equilateral triangle, we 
should unhesitatingly conclude that an intelligent being had 
been before us and left this mark, nor would any argument to 
the contrary—if one could be found, or even imagined—avail 
to shake our belief. 
The admission of such a force being, however, what many 
evolutionists are most unwilling to admit, they commonly seek 
for the needful foundation on which to base the objective reality 
of their classification in community of descent, so that a species 
consists of individuals which have at some period, comparatively 
recent, descended from a common ancestor—or pair; and a 
genus consists of species which have similarly originated at a 
period more remote, in the course of which the power to which 
transtormation is due, whether natural selection or another, 
has operated to produce alterations now recognized as specific. 
Something of a digression here suggests itself, which appears 
to be by no means unimportant. 
It is not easy to ascertain on unimpeachable authority what 
the course of evolution must be supposed to have been. In the 
conclusion of the Origin, Mr. Darwin speaks of life having 
been originally breathed “into several forms, or into one.” 
Mr. Wallace intimates* that not only distinct forms, such as 
crows and thrushes, may have descended “from each other,” 
but that all birds, including such widely different types as 
wrens, eagles, ostriches, and ducks, are possibly, or probably, 
modified descendants of a common ancestor; further still, that 
even mammals, birds, reptiles, and fishes may have a common 
origin. 
On the other hand, Mr. Darwin emphatically warns us 
against the notion that we shall ever find, either living or fossil, 
the direct progenitor of any species, existent or extinct.f All 
that we have a right to expect is a form intermediate between 
each species and a common but unknown progenitor not, 
however, as it would seem directly, intermediate between them. 
But he tells us, moreover,f that the same identical species cannot 
be produced twice over, “ even if the very same condition, of life, 
* Darwinism, p. 6. 
+ Origin, 6th Edition, p. 264. 
t Op. cié., p. 292. 
