124 REV. JOHN GERARD, F.L.S., ON SPECIES AND THEIR ORIGIN. 
be taken to mean. Undoubtedly, however, he clearly showed 
that he supposed each species to be descended from a single 
ancestor, or rather, it should seem, pair of ancestors. To this 
extent, therefore, he was in agreement with Linnzus and the 
older naturalists, who, as is well known, defined species as the 
descendants of a brace of parents originally created in the 
exact form which their offspring still perpetuate; but with 
this notable difference, that Darwin’s whole point is that the 
ancestors to whom common descent is thus to be traced, were 
themselves sprung from progenitors so different from them 
that they would needs be regarded as constituting another 
species. The question does not now concern us as to how the 
transformation of the older form to the newer may be supposed 
to have come about, whether by the action of natural selection 
or otherwise. What we have to examine is simply, What is it 
that is said to have been transformed; or, in other words, 
What is a species? To this various high authorities give 
various answers. 
Mr. Wallace* quotes one definition from a distinguished 
botanist, De Candolle, another from a zoologist, Swainson, of 
whom the former says :— 
“A species is a collection of all the individuals which 
resemble each other more than they resemble anything else, 
which can by mutual fecundation produce fertile individuals 
and which reproduce themselves by generation in such a 
manner that we may from analogy suppose them to have all 
sprung from one single individual.” 
Swainson writes to somewhat similar effect :— 
“ A species, in the usual acceptation of the term, is an animal 
which, in a state of nature, is distinguished by certain peculi- 
arities of form, size, colour, or other circumstances from another 
animal. It propagates after its kind individuals perfectly re- 
sembling the parent ; its peculiarities, therefore, are permanent.” 
On the other hand, Mr. Mivart tells ust :— 
“The word ‘species’ denotes a peculiar congeries of 
characters, innate powers and qualities, and a certain nature 
realised indeed in individuals, but having no separate existence, 
except ideally, as a thought in some mind.” 
These definitions are evidently quite different, and the 
difference is of no slight importance. It is very frequently 
laid down as undeniable that “species” themselves have no 
* Darwinism. 
t+ Genesis of Species, p. 2. 
