INUTILITY OF MUTATIONS 179 



special plants and animals, or on soil or climate, and who, owing to 

 his mental powers, is otherwise very adaptable. 



297. The sole warrant for the belief that fluctuating variations 

 cannot be made more stable by continued selection is furnished 

 by the fact that recently evolved domestic varieties, such as the 

 American trotting-horse, tend to retrogress rapidly when no longer 

 selected. We have already discussed this question in part ; 1 

 presently we shall see how sex is instrumental in determining the 

 rapid retrogression of characters of recent origin. The sole warrant 

 for the hypothesis that the organic world has arisen by the selection 

 of mutations is furnished by the fact that some mutations have 

 been observed in wild nature, and that mutations appear excep- 

 tionally stable. Doubtless, however, they are common enough. 

 In man, the only natural species with which we are at all intimately 

 acquainted, they are very common, and often the same mutation 

 is repeated in many individuals. The medical profession owes its 

 prosperity largely to them : they fill our hospitals ; surgeons are 

 busy every day rectifying such mutations as hare-lip and club- 

 foot. But never yet has a mutation been recorded neither in man, 

 nor in lower animals, nor in plants that gave its possessors an 

 advantage in the struggle for existence so overpowering that 

 it enabled them to supplant the ancestral type. And hardly a 

 mutation has been recorded which enabled its possessors to persist 

 alongside the parent variety, at any rate when the reproduction 

 was bi-parental. 2 



298. Mutationists declare that the general failure to detect 



1 See 182. 



2 The most widely discussed mutations are those of (Enothera lamarckiana, an 

 evening primrose, investigated by de Vries. Several species of evening primroses 

 were brought to Europe from America during the seventeenth and eighteenth 

 centuries. It is not known when, if ever, O. lamarckiana was introduced. It 

 was first observed by Lamarck at the beginning of the last century in a garden at 

 Paris, and at once recognized as a type new to science. The fact that this ' stately,' 

 ' beautiful,' and noticeable plant was previously unknown to botanists, the 

 circumstances under which it was discovered, and the fact that it is not known 

 to grow wild anywhere in America, render it likely that it originated as a garden 

 variety in Europe, possibly in the very garden in which Lamarck found it. Most 

 probably, like so many other cultivated varieties, it is a mongrel, possessing an 

 unknown number of latent characters. At any rate it is a descendant of a wild 

 American plant, which, for more than a century, had been cultivated in Europe, 

 and which, presumably owing to changes in selection due to the great changes in 

 its environment and possibly to crossing, had become highly variable. The 

 patch of plants in which de Vries discovered his mutants from O. lamarckiana 

 had escaped from cultivation and was growing wild in a disused potato field. 

 More mutations occurred after he had altered the environment yet again by re- 

 moving specimens to his garden, where he cultivated the plants on a large scale. 



