218 Obscrvalion of the Or'ujin of ]\iviciics. 



parison of this mutation with those of Oenothera La- 

 inarekiana. The two processes have several features in 

 common, but possess others which are mere or less 

 strongly opposed. 



The points of similarity are : the sudden and imnie- 

 diate origin, the repeated appearance, the mutation- 

 coefficient of about 1% (see Vol I, Part II, § 14, p. 2>^7), 

 the completeness of the new type, and its high degree 

 of heritability. 



These common characters justify the description of 

 the origin of Linaria vulgaris peloria as a mutation.^ 



But it is a mutation of a special kind. The structural 

 change does not extend to all parts of the plant, but is 

 confined to the flowers ; in their youth the two types 

 cannot be distinguished. In the mutations of Oenothera 

 Laniarckiana the new characters are analogous to the 

 specific characters of related species already existing; 

 in the case of Linaria no such analogy exists. On the 

 contrary the new character in Linaria occurs as a variety 

 in numerous other species, and even in distantly related 



^ Linnaeus, as is well known, expressed the view that the Peloria 

 is a hybrid between the common Linaria vulgaris and some other im- 

 known plant. Its comparative sterility favored this view, but as the 

 second of the two parents could not be found this view has since 

 been given up. Here, however, I might discuss the possibility that 

 L. vnlg. hemipcloria might be a cross between L. vulgaris (apeloria) 

 and L. vulg. peloria. If this were so the appearance of the latter 

 from the former would perhaps have to be regarded not as a muta- 

 tion, but as a segregative process in a hybrid race. If this view 

 were true the Peloria should first have arisen from the Apeloria, 

 without the mediation of the Pleuiipeloria, a process which has still 

 to be observed. It is, however, no more than a pure assumption 

 that the hybrid ApeloriaY, Peloria would be a Heuiipeloria; in fact 

 our knowledge of other cases would lead us to suppose that it would 

 be like one of the parents, in this case the Apeloria, and so long as 

 there is no direct information on any of these points a further dis- 

 cussion of this view seems barren. Moreover it is by no means cer- 

 tain that Linaria vulgaris apeloria exists at all, or ever has existed; 

 the variety, in this genus particularly, may well be older than the 

 species. 



