XXVI FLORA OF TASMANIA. 



fication, is swallowed up in the gigantic conception of a power intermittently exercised in the develop- 

 ment, out of inorganic elements, of organisms the most bulky and complex as well as the most minute 

 and simple ; and the consanguinity of each new being to its pre-existent nearest ally, is a barren fact, 

 of no scientific significance or further importance to the naturalist than that it enables him to clas- 

 sify. The realization of this conception is of course impossible ; the boldest speculator cannot realize 

 the idea of a highly organized plant or animal starting into life within an area that has been the field 

 of his own exact observation* and research ; whilst the more cautious advocate hesitates about ad- 

 mitting the origin of the simplest organism under such circumstances, because it compels his sub- 

 scribing to the doctrine of the " spontaneous generation " of living beings of every degree of com- 

 plexity in structure and refinement of organization. 



On the other hand, the advocate of creation by variation may have to stretch his imagination to 

 account for such gaps in a homogeneous system as will resolve its members into genera, classes, and 

 orders ; but in doing so he is only expanding the principle which both theorists allow to have operated 

 in the resolution of some groups of individuals into varieties : and if, as I have endeavoured to show, 

 all those attributes of organic life which are involved in the study of classification, representation, and 

 distribution, and which are barren facts under the theory of special creations, may receive a rational 

 explanation under another theory, it is to this latter that the naturalist should look for the means of 

 penetrating the mystery which envelopes the history of species, holding himself ready to lay it down 

 when it shall prove as useless for the further advance of science, as the long serviceable theory of 

 special creations, founded on genetic resemblance, now appears to me to be. 



The arguments deduced from genetic resemblance being (in the present state of science), as far 

 as I can discover, exhausted, I have felt it my duty to re-examine the phenomena of variation in 

 reference to the origin of existing species ; these phenomena I have long studied independently of 

 this question, and when treating either of whole Floras or of species, I have made it my constant aim 

 to demonstrate how much more important and prevalent this element of variability is than is usually 

 admitted, as also how deep it lies beneath the foundations of all our facts and reasonings concerning 

 classification and distribution. I have hitherto endeavoured to keep my ideas upon variajion 4k "5 ab- 

 jection to the hypothesis of species being immutable, both because a due regard to that theory checks 

 any tendency to careless observation of minute facts, and because the opposite one is apt to lead 

 to a precipitate conclusion that slight differences have no significance; whereas, though not of 

 specific importance, they may be of high structural and physiological value, and hence reveal affi- 

 nities that might otherwise escape us. I have already stated how greatly I^am indebted to Mr. 

 Darwin' sf rationale of the phenomena of variation and natural selection in the production of species; 

 and though it does not positively establish the doctrine of creation by variation, I expect that 

 every additional fact and observation relating to species will gain great additional value from being 

 viewed in reference to it, and that it will materially assist in developing the principles of classification 

 and distribution. 



* It is a envious fact (illustrative of a well-known tendency of the mind), that the few writers who have in ima- 

 gination endeavoured to push the doctrine of special creatious to a logical issue, either place the scene of the creative 

 effort in some unknown, distant, or isolated corner of the globe, removed far beyond the ken of scientific observation, 

 or suppose it to have been enacted at a period when the physical conditions of the globe differed both in degree and 

 kind from what now obtain ; thus in both cases arguing ad ignotum ah ujnoto. 



f In this Essay T refer to the brief abstract only (Linn. Journ.) of my friend's views, not to his work now in 

 the press, a deliberate study of which may modify my opinion on some points whereon we differ. Matured conclu- 

 sions on these subjects are very slowly developed. 



