THE MUTATION HYPOTHESIS 65 



different results to those of de Vries, suggest that it was pro- 

 duced by crossing various forms of (E. biennis, which is poly- 

 morphic, and is known to have been previously introduced 

 into Europe. 1 In any case (E. lamarckiana is an organism 

 that has been domesticated for a very considerable time, and 

 is an exotic imported from another continent. 



De Vries was unable to find a single instance of a per- 

 manent mutation among the wild plants that he inves- 

 tigated. The other probable cases of perpetuation of 

 mutations are among domesticated plants that have been 

 subjected to artificial selection for a considerable period of 

 time, and possibly also to artificial hybridisation. Until we 

 find some well-authenticated causes of mutations being per- 

 petuated among wild species, the theory that evolution of 

 any species has been brought about by mutations and not by 

 constant fluctuating variations, cannot be held as probable. 



There appears to be no evidence at all with regard to 

 mutations being perpetuated among animals, even among 

 the lower forms. If, for instance, we take Aurelia aurita 

 a common jelly-fish in which sports or mutations are very 

 frequent, we find considerable evidence that these sports are 

 not perpetuated, but are eliminated. The sports in this 

 animal were recorded by Ehrenberg in 1835. His facts have 

 been confirmed by several observers, and Browne in 1895, by 

 examining large numbers of the young and adult animals, 

 showed that the abnormal forms, that is, those in which 

 mutations had occurred, seemed to survive just as well as 

 the normal individuals. 2 In spite of this, the race, that is, 

 the bulk of the individuals in the species A. aurita, remains 

 the same, and no new race appears to be established although 

 mutations are extremely common. 



It is argued by de Vries and his followers that an 

 accumulation of small fluctuating variations produced by 

 selection, although transmitted from parent to offspring, 



1 Boulangcr, G. A., Journal of Botany, October 1907. 



2 Browne, E. T., "On the Variation of the Tentaculocysts of Aurelia 

 aurita," Quart. Journ. Microscopical Science, xxxvii., 1895. 



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