CHAP, xcix RARE SPECIES 369 



moms, Polygonum viviparum, Saxifraga Hirculus, Scheuchzeria palustris. 

 Primula farinosa, and Carex chordorrhiza. These species will beyond 

 doubt gradually become rarer or disappear entirely from the floras, as 

 has already been the fate of some relic-plants. 



It is very difficult to prove of a species that it is a rehc-plant, or even 

 to show this with reasonable probability, and in many cases this character 

 has been ascribed on insufficient grounds to species that are perhaps recent 

 immigrants.^ 



CHAPTER C. ORIGIX OF SPECIES 



Through the whole of the preceding text has run the conception that 

 the structure and whole course of development of species sta7id in perfect 

 harmony {epharmony-) with the environment, and that species are adapted 

 to the surrounding conditions. To Darwin we owe an everlasting debt in 

 that he drew our attention to the epharmony prevailing in every niche 

 and cranny of Nature. The question naturally arises : ' How has this 

 epharmony arisen ? ' Various replies have been given to this query. 

 Old-fashioned teleologists would answer : ' Through the direct creative 

 action and wisdom of God.' Modern research, relying upon the facts of 

 evolution, whose foundation was laid by Darwin, gives other explanations. 

 Among these are the following three : 



(i) According to Darwin there arise an infinite number of indefinite, 

 diversified, and small variations in individuals ; and, inasmuch as the 

 world does not provide sufficient space for all the individuals born. Nature 

 must exert some selective action, and by means of the 'struggle for 

 existence ' will lead to the preservation of the most useful or fitting 

 characters. By means of continuous selection, in the course of time 

 more considerable distinctions will be evoked. And in this way adapta- 

 tion has come into being. This explanation has recently been assailed 

 on many sides, and does not now find so many supporters as it had when 

 first promulgated by Darwin. 



(ii) Recently Korschinsky ^ and H. de Vries * have put forward a some- 

 what different explanation of the origin of species. According to them 

 new forms arise by sudden great changes (in a ' heterogenetic ' manner, as 

 Korschinsky terms it, or by ' mutations ', as de Vries has it) and instantly 

 become constant. As the new forms are very diversified, and may possess 

 characters useful, indifferent, or even harmful to the possessor, epharmony 

 can only come into force by naturally eliminating the forms with disad- 

 vantageous characters, and by leaving those with useful or indifferent 

 ones. 



That new forms can arise by mutation is a fact ; but we do not yet 

 know the extent to which they can differ from the parent-form, nor how 

 far they are able to acquit themselves in their struggles with other forms. 

 Possibly in this way there have arisen many forms, also many characters 

 that are ' indifferent ' in effect on the plant's existence and might be 

 termed ' useless ' (' systematic ' or ' morphological ' characters). 



' Warming, 1904. ' Vesque, 1882 a. ' Korschinsky, 1899. 



* H. de Vries, 1901, 1903. 



WARMING B b 



