100 Transactions. 



of direct adaptation or self-adaptation, as understood by Warming (1909) 

 — it would seem probable that a single ancestral form of Ranunculus deve- 

 loped under conditions of extreme drought into a typical xerophyte, and 

 that, after the conditions to which it had adapted itself Ikd been modified 

 or completely changed, this plant maintained itself against the compe- 

 tition of a mesophyte flora in certain localities — i.e., shingle-slips — in which 

 it had an advantage, and in course of a long period of time, existing only 

 in isolated areas completely separated from one another (one of which is 

 the limestone area here described), it developed those comparatively trivial 

 distinctive characters (especially in the cutting of the leaf) which now 

 distinguish the " species " from one another. 



According to De Vries (1912), however, such speculations and conjec- 

 tures as to the conditions under which a species originated are idle, and 

 can achieve no result. Speaking of " beautiful adaptations " to local 

 conditions, he says : " In no case is it possible to tell whether the species 

 have acquired these during their migration or during their stay in the new 

 environment, or perhaps previous to their being subjected to the influence 

 in question " (p. 592). Again : " Adaptations to new conditions [which 

 are conceded] depend upon characters which were inherent in the species 

 before it arrived in the new environment. The characters themselves 

 are not the effect of the external influences considered " (p. 579). Such 

 characters, it is contended, cannot be good specific marks ; they fall within 

 the range of " fluctuations " (as distinguished from mutations) and " cannot 

 lead to constant races " (p. 540). The species thus modified or adapted 

 remains essentially the same, and will, if replaced in the favourable con- 

 ditions, resume its older form (as in the classic experiments of Cockayne 

 upon seedling forms, and those of Bonnier upon alpine plants). The sole 

 condition required in the plant is therefore " high plasticity." We must 

 not say that a species originated under the stimulus of its environ- 

 ment, or that it acquired new characters in response to changed con- 

 ditions : that would be confusing cause and effect. " Fitness for present 

 life-conditions . . . can hardly be considered as a result of adapta- 

 tion, and we have to recur to previous hypothetical environments to 

 explain the much-admired adjustments. All speculations, of this kind 

 are merely reduced to more or less plausible and more or less poetical* 

 considerations " (p. 574). It is concluded that " geological changes of 

 climate may have been accompanied by the production of new forms, but 

 there is no evidence that this has occurred in such a way as to provoke 

 directly useful changes"; that "the characters of local and endemic types 

 do not betray any definite relation to their special environment " ; and, 

 finally, that " the facts which are at present available plead against the 

 hypothesis of a direct adjusting influence of environment upon plants, and 

 comply with the proposition of changes brought about by other causes and 

 afterward subjected to natural selection " (p. 595). The author then restates 

 his personal belief "that the species-making changes occur by leaps and 

 bounds, however small." 



If these conclusions be accepted, the case of Ranunculus paucifolius 

 and its associates may be thus considered in their light. It is generally 

 accepted that a period of more or less severe drought or " steppe climate " 

 has been passed through by a great part at least of the flora of New 



* The writer explains in a footnote that this epithet is not intended to convey any 

 reproach. 



