Greville_, on the genus Auliscus. 
37 
tion of the word^ designates the whole of the individuals 
supposed to be descended from one original plant or pair of 
plants. But this definition is practically useless ; for we 
have no means of ascertaining the hereditary history of 
individual plants. . . . Believing, however,, as I do, that there 
exist in nature a certain number of fgroups of individuals 
the limits to whose powers of variation are, under present 
circumstanceSj fixed and permanent, I have been in the 
habit of practically defining the species as the whole of the 
individual plants ivhich resemble each other sufficiently to 
make us conclude that they are all, or may have been all, 
descended from a common parent''"^ Here, it will be per- 
ceived, everything ultimately depends upon the judgment of 
the observer. 
Agassiz speaks with the utmost confidence, and apparently 
sees no difiiculties at all. It was a great step,^^ he says^ 
in the progress of science^ when it was ascertained that 
species have fixed characters, and that they do not change in 
the course of time Geology only shows that at dif. 
ferent periods there have existed diff*erent species; but no 
transition from those of a preceding into those of the follow- 
ing epoch has ever been noticed anywhere .... nothing fur- 
nishes the slightest argument in favour of their mutability. 
On the contrary, every modern investigation has gone only 
to confirm the results first obtained by Cuvier, and his views, 
that species are fixed. ^^f 
In amusing contrast to Agassiz, we have the astounding 
deductions of Mr. Darwin, who writes — I can entertain no 
doubt, after the most deliberate study and dispassionate judg- 
ment of which I am capable, that the view which most natu- 
ralists entertain, and which I formerly entertained, namely, 
that each species has been independently created, is erroneous. 
I am fully convinced that species are not immutable. ... I 
believe that all animals have descended from at most only four 
or five progenitors, and plants from an equal or lesser number. 
. . . Probably ail the organic beings which have ever lived on 
the earth have descended from some one primordial form, into 
which life was at first breathed.^^ Alas ! for the fixity of species ! 
The shades of Linnseus and Cuvier are not to rest in peace. 
Dr. Joseph Hooker, in his most valuable and interesting 
Introductory Essay to the ' Flora of New Zealand,^ adheres 
to what may be called the popular view of the question, in 
assuming that all the individuals of a species (as I attempt 
to confine the term) have proceeded from one parent (or 
* *Nat. Hist. Review,' vol. i, p. 133. 
t ' Essay on Classification/ pp. 75—78. 
