1V FLORA OF TASMANIA. 
' Flora of New Zealand : ' on such theoretical questions, however, as the origin and ultimate per- 
manence of species, they have been greatly influenced by the views and arguments of Mr. Darwin 
and Mr. Wallace above alluded to, which incline me to regard more favourably the hypothesis that 
it is to variation that we must look as the means which Nature has adopted for peopling the globe 
with those diverse existing forms which, when they tend to transmit their characters unchanged 
through many generations, are called species. Nevertheless I must repeat, what I have fully stated 
elsewhere, that these hypotheses should not influence our treatment of species, either as subjects of 
descriptive science, or as the means of investigating the phenomena of the succession of organic 
forms in time, or their dispersion and replacement in area, though they should lead us to more 
philosophical conceptions on these subjects, and stimulate us to seek for such combinations of their 
characters as may enable us to classify them better, and to trace their origin back to an epoch 
anterior to that of their present appearance and condition. In doing this, however, the believer in 
species being lineally related forms must employ the same methods of investigation and follow the 
same principles that guide the believer in their being actual creations, for the latter assumes that 
Nature has created species with mutual relations analogous to those which exist between the lineally- 
descended members of a family, and this is indeed the leading idea in all natural systems. On the 
other hand, there are so many checks to indiscriminate variation, so many inviolable laws that regu- 
late the production of varieties, the time required to produce wide variations from any given specific 
type is so great, and the number of species and varieties known to propagate for indefinite periods 
a succession of absolutely identical members is so large, that all naturalists are agreed that for 
descriptive purposes species must be treated as if they were at their origin distinct, and are des- 
tined so to remain. Hence the descriptive naturalist who believes all species to be derivative and 
mutable, only differs in practice from him who asserts 
contrary, in expecting that the posterity 
of the organisms he describes as species may, at some indefinitely distant period of time, require 
I need hardly remark that the classificatory branch of Botany is the only one from which 
this subject can be approached, for a good system must be founded on a due appreciation of all 
the attributes of individual plants,-upon a balance of their morphological, physiological, and 
anatomical relations at all periods of their growth. Species are conventionally assumed to repre- 
sent, with a great amount of uniformity, the lowest degree of such relationship; and the facts that 
individuals are more easily grouped into species limited by characters, than into varieties, or than 
species are into limitable genera or groups of higher value, and that the relationships of species 
are transmitted hereditarily in a very eminent degree, are the strongest appearances in favour of 
species being original creations, and genera, etc., arbitrarily limited groups of these. 
The difference between varieties and species and genera in respect of definable limitation is 
however one of degree only, and if increased materials and observation confirm the doctrine which 
I have for many years laboured to establish, that far more species are variable, and far fewer limit- 
able, than has been supposed, that hypothesis will be proportionally strengthened which assumes 
species to be arbitrarily limited groups of varieties. With the view of ascertaining how far my 
own experience m classification will bear out such a conclusion, I shall now endeavour to re- 
view, without reference to my previous conclusions, the impressions which I have derived from 
the retrospect of twenty years' study of plants. During that time I have classified many large 
and small Floras, arctic, temperate, and tropical, insular and continental : embracing areas so 
extensive and varied as to justify, to my apprehension, the assumption that the results derived 
