* 
* 2 J.D. Hooker, Introductory Essay to the Flora of Tasmania. 
gin of species, 
which I refrained from endorsing as articles of iy own creed: 
amongst others was the still prevalent doctrine that these are, 
in the ordinary acceptation of the term, created as such, and are 
immutable. In the present Essay I shall advance the opposite 
hypothesis, that species, are derivative and mutable; and this 
chiefly because, whatever opinions a naturalist may have adopted 
with regard to the origin and variation of species, every candid 
mind must admit that the facts and arguments upon which he 
has grounded his convictions require revision since the recent 
publication by the Linnean Society of the ingenious and orig- 
inal reasonings and theories of Mr. Darwin and Mr. Wallace. 
Further, there must be many who, like myself, having hith- 
erto refrained from expressing any positive Opinion, now, after 
a careful consideration of these naturalists’ theories, find the as- 
pect of the question materially changed, and themselves freer 
to adopt such a theory as may best harmonize with the facts ad- 
duced by their own experience. ee 
The Natural History of Australia seemed to me to be espe- 
__ cially suited to test such a theory, on account of the comparative 
~ uniformity of its physical features being accompanied with a 
great variety in its Flora; of the differences in the vegetation 
of its several parts; and of the peculiarity both of its Fauna 
and Flora, as compared with those of other countries. I accord- 
ingly prepared a classified catalogue of all the Australian species 
in the Herbarium, with their ranges in longitude, latitude, and 
_ elevation, as far as I could ascertain them, and added what fur- 
a ‘: 
