W. Teayees. — Syhridization of Plants. 31 



Aet. III. — On Sylridization, loith reference to Variation in Plants. 

 By W. T. L. Teavees, F.L.S. 

 [Read hefore the Wellington Philosophical Society, 2Sth July, 1868.] 

 Amongst the plants indigenous to tTie Middle Island of New Zealand, there 

 are none whicli range more widely, both in altitude and in latitude, nor 

 wMeli present a greater amount of variation, than the Veronicas. Indeed, 

 as Dr. Hooker remarks, in the notes to the Conspectus of this genus, pub- 

 lished in his " Handbook of the New Zealand Elora," so numerous are the 

 intermediate forms between very distinct looking species, as to render the 

 species excessively difficult of discrimination, and to compel the adoption, 

 for the purposes of an interim classification, of purely arbitrary characters 

 founded on " prominent prevalent differences only." Dr. Hooker, in a com- 

 munication to myself in reference to a large and varied collection of speci- 

 mens which I forwarded to him in the early part of 1864, whilst he was 

 engaged in compiling the " Handbook," remarked on the possibility that the 

 variation referred to might be due to natural hybridization, and asked me 

 whether I thought this was the case. In reply, I expressed an opinion 

 against the supposition, and the following paper contains the substance of 

 the grounds urged by me against it. 



Before, however, entering upon the special question under discussion, I 

 will venture to call attention to the two principal theories now prevalent 

 respecting the origin of the various species of organic life found within 

 particular areas. The first is, that the surface of the globe, at an early 

 period, became divided into a number of great areas of population, each of 

 which contained a distinct fauna and flora, distinguishable by characteristics 

 proper to that particular area only ; and that the various species now found 

 within it have from time to time been since created in order to supply the 

 place of representative species which have died out. The second is, that 

 every group of organisms has a purely derivative origin, and that each exist- 

 ing species is but the modified descendant, preserved by means of natural 

 selection, of some other species : whilst, probably, in most cases so great a 

 divergence has taken j)lace from the original type, as to transgress the con- 

 ventional circle which we draw round generic type, and induce us to refer it 

 to some other genus than that to which it would originally have been assigned. 

 It has been well observed that if the first of these theories be true, all 

 attempts to trace the origin of present and past faunas and floras must 

 necessarily be futile, for their origin would be sufficiently elucidated in the 

 dogma that " they were created on the spot," and that such a theory would 

 render palseontology a useless study, and reduce it to a mere leviathan cata- 

 logue of fossils. Notwithstanding, therefore, the " weighty difficulties which 

 surround the theory of natural selection," (as observed by the great ex- 



