IN BORNEAN FORESTS [chap. 



If, however, new forms of adaptation are not produced under 

 our own eyes, it must be admitted that, from time to time, accidental 

 varieties, or deviations from the common type, appear in Nature, 

 for we every day see horticulturists obtain new varieties of flowers 

 and fruit, and breeders and fanciers new kinds of cattle, dogs, 

 poultry, and pigeons. 



But careful experiments have shown that the supposed variabi- 

 lity of species at the present time is more apparent than real. In 

 trying to demonstrate the variability of species by exhibiting the 

 various forms that a given species assumes in Nature, we only prove 

 that it has varied, and thus confound polymorphism with variability. 1 



Experiments and cultivation do not thus confirm the existence 

 in living beings of that extensive variability which many naturalists 

 pretend to believe ; and in any case, such variability is not now of 

 an adaptive kind. Therefore, contrary to the present prevailing 

 tendency to attribute a powerful action to variability during the 

 existing period, and to consider every species as inconstant, I hold 

 the opposite opinion, namely, that at the present time species do 

 not vary in Nature, returning thus to the old idea of the nearly 

 absolute fixity of existing species. 2 



The indisputable fact, however, remains that through cultivation 

 and artificial selection in breeding new forms can be obtained. 



The circumstances, however, which at the present time are 

 associated with the production of domestic varieties of animals and 

 plants, are of a very different nature from those which must have 

 brought about variation through adaptation. Thus, for example, 

 if a new variety of Primula sinensis makes its appearance with a 

 corolla frilled, jagged, or more divided than in the wild form, this 

 is not because such new characters correspond to any special want or 

 necessity of the plant, or because it is advantageous for it to assume 

 them. In the forms produced or obtained by breeders, or by 

 horticulturists, the first indication which has led to the formation 

 of the new variety or race has in every case cropped out accidentally, 

 without any ascertained cause or reason, and quite independently 

 of any act or wish of the producer. The latter has merely taken 

 advantage of a first tendency or plan of variation which has 

 naturally manifested itself, and, by preserving and causing the 

 individuals who have shown such a tendency to interbreed, has 

 succeeded in increasing and exaggerating the sport. But who can 



L I base this assertion especially on the well-known experiments of 

 Naegeli on Hieracium. 



2 I should not consider as an adaptation of recent formation the case of 

 some plants which undergo certain changes if grown in new conditions, 

 as, for instance, that seen in alpine species planted in lowlands. This is 

 merely a latitude in already acquired characters, constant in any given 

 species. 



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