VARIATIONS IN ANIMALS AND PLANTS 485 



influence of artificial selection a non-adaptive or indifferent character 

 becomes adaptive or selective. Among those animals or plants which 

 submit readily to domestication almost any natural species, distin- 

 guished by non-adaptive characters, could be reproduced with all its 

 traits by a process of carefully controlled selective breeding. 



Saltations 1 



It has long been known that individual fluctuations of an extreme 

 degree sometimes occur, and that these may be to a degree persistent 

 in heredity. Of such nature was the Ancon sheep, the iceberg black- 

 berry and numerous other races or forms known in the domestication 

 of animals or the cultivation of plants. The generally normal struc- 

 ture of such individuals distinguishes them from monstrosities, which 

 are usually freaks of development rather than of heredity. 



The name ' saltation,' or in recent years ' mutation,' has been 

 applied to extreme fluctuation, the immediate cause of which is un- 

 known. The experiments of Dr. Hugo de Vries on the saltations of 

 the descendants of an American form of evening primrose (Oenothera 

 lamarckiana) have recently drawn general attention again to the 

 possibility that saltation has had a large part in the process of forma- 

 tion of species. As to this it may be said that the possible variation 

 within each species is much greater than the range of the individuals 

 which actually survive. The condition of domestication favors the de- 

 velopment of extreme variation, because such individuals may be pre- 

 served from interbreeding with the mass, and they may survive even 

 if their characters "are unfavorable to competition in the struggle for 

 existence. Among plants it is noticed that new soil and new condi- 

 tions seem to favor large variation in the progeny, although the traits 

 thus produced are rarely if ever hereditary. Cases more or less analo- 

 gous to those noted by Dr. de Vries are not rare in horticulture. The 

 cross-breeding of variant forms favors the appearance of new forms. 

 Among actual species in a state of nature, there are very few which 

 seem likely to have arisen by a sudden leap or mutation. The past 

 and the future of de Vries's evening primroses are yet to be shown, and 

 it is not at all unlikely that the original CEnothera lamarckiana found 

 in a field near Amsterdam was a hybrid stock, a product of the florist, 

 the behavior of its progeny being not unlike that which appears in the 

 progeny of hybrids. The species called by de Vries CEnothera la- 

 marckiana is not known in its wild state anywhere in North America, 

 the parent region of the species of evening primrose or Oenothera. It 

 is, moreover, known that the seeds of hybrids of an American species, 

 probably CEnothera biennis, the common evening primrose, with other 



1 The name saltation has been long used for wide fluctuations without 

 recognizable cause. The more recent name mutation chosen by de Vries has 

 been in use for years for the slow changes appearing in geological time. 



