IV FLORA OP 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 the contrary, in expecting that the posterity 

 of the organisms he describes as species may, at some indefinitely distant period of time, require 

 redescription. 



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 in 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 



