XXIV FLORA OF TASMANIA. 



of the Genera and Orders most deficient in these respects are so manifestly reduced members of 

 others, which are indisputably the most complex in organization in the whole Vegetable Kingdom, 

 that no good classification even has been founded on these considerations alone.* 



37. Again, it is argued by both Mr. Darwin and Mr. "Wallace that the general effects of variation 

 ■by selection must be to establish a general progressive development of the whole animal kingdom. 

 But here again in botany we are checked by the question, What is the standard of progression? 

 Is it physiological or morphological ? Is it evidenced by the power of overcoming physical obstacles 

 to dispersion or propagation, or by a nice adaptation of structure or constitution to very restricted or 

 complex conditions ? Are cosmopolites to be regarded as superior to plants of restricted range, her- 

 maphrodite plants to unisexual, parasites to self-sustainers, albuminous-seeded to exalbuminous, gym- ■ 

 nosperms to angiosperms, water plants to land, trees to herbs, perennials to annuals, insular plants 

 to continental? and, in fine, what is the significance of the multitudinous differences in point of 

 structure and complexity, and powers of endurance, presented by the members of the Vegetable 

 Kingdom, and which have no recognized physiological end and interpretation, nor importance in a 

 classificatory point of view ? It is extremely easy to answer any of these questions, and to support 

 the opinion by a host of arguments, morphological, physiological, and teleological ; but any one gifted 

 with a quick perception of relations, and whose mind is stored with a sufficiency of facts, will turn 

 every argument to equal advantage for both sides of the question. 



To my mind, however, the doctrine of progression, if considered in connection with the hypothesis 

 of the origin of species being by variation, is by far the most profound of all that have ever agitated 

 the schools of Natural History, and I do not think that it has yet been treated in the unprejudiced 

 spirit it demands. The elements for its study are the vastest and most complicated which the 

 naturalist can contemplate, and reside in the comprehension of the reciprocal action of the so-called 

 inorganic on the organic world. Granting that multiplication and specialization of organs is the 

 evidence and measure of progression, that variation explains the rationale of the operation which 

 results in this progression, the questiou arises, What are the limits to the combinations of physical 

 causes which determine this progression, and how can the specializing power of Nature sto£-srfuh~bf 

 causing every race or family ultimately to represent a species? While the psychological philosophers 

 persuade us that we see the tendency to specialize pervading every attribute of organic life, mental 

 and physical ; and the physicists teach that there are limits to the amount and duration of heat, 

 light, and every other manifestation of physical force which our senses present or our intellects per- 

 ceive, and which are all in process of consumption ; the reflecting botanist, knowing that his ultimate 

 results must accord with these facts, is perplexed at feeling that he has failed to establish on inde- 

 pendent evidence the doctrines of variation and progressive special; nation, or to co-ordinate his 

 attempts to do so with the successive discoveries in physical science. 



* The subject of the retrogression of types lias never yet been investigated in botany, nor its importance esti- 

 mated in inquiries of this nature. To whatever Order we may grant the dignity of great superiority or complexity, 

 we find that Order containing groups of species of very simple organization ; these are moreover often of great size 

 and importance, and of wide geographical distribution. Such groups, if regarded per se, appear to be far lower in 

 organization than other groups which are many degrees below them in the classified series ; and our only clue to 

 their real position is their evident affinity with their complex co-ordinates; — destroy the latter by a geological or 

 other event, and all clue to the real position of the former may be lost. Are such groups of simply-constructed 

 species created by retrogressive variation of the higher, or did the higher proceed from them by progressive variation? 

 If the latter, did the simpler forms precede in origin the highest forms of all other groups which rank below them 

 in the classified series ? 



