Variegated Leaves. 273 



mnm segetuiu, Antirrhimtm niajiis, Polygonum fago- 

 pynini, Linaria I'ldgaris, Silene noctiflora etc. 



The large scale on which I have conducted my ex- 

 periments with Oenothera Lamarckiana has enabled me 

 to watch the origin of variegated forms in that species 

 more closely. Here they appear almost every year from 

 green ancestors, and in the most widely different experi- 

 mental families and elementary species.^ Instances of 

 it I found in the main Lamarckiana families, first in the 

 original wild locality, then in 1889, 1890, 1892, 1895, 

 1898 and 1899 in my cultures, arising from series of 

 seed-parents which were in every case green plants ; 

 also in 0. ruhrinervis in 1891, 1893 and 1894; in 0. 

 laevifolia in 1891, 1894 and 1899; in O. suhlincaris in 

 1896; in 0. lata in 1890 and 1899; in O. nancUa in 1890, 

 1896 and 1899; in O. scintillans in 1898 and so on; also 

 from the crosses 0. lata X O. criiciata and O. Lamarck- 

 iana X O. Lamarckiana criiciata and others. In 1899 

 only eight variegated plants arose in my whole cultures 

 which consisted of over five thousand plants of Oeno- 

 thera, that is, between 0.1 and 0.2%. But in the field 

 the anomaly was evidently much rarer. 



One of the most striking phenomena presented by 

 variegated plants is the so-called twig or bud-variation. 

 From a bud a branch arises which is unlike the whole 

 of the rest of the plant in the character of its variegation, 

 and in this case both variegated plants bearing green 

 twigs occur and conversely plants which have hitherto 

 been green may bear stray variegated branches. In both 

 cases a latent potentiality is manifested. 



The appearance of green branches on variegated 

 plants is generally regarded as a case of atavism, that is 



^ See also Vol. T, p. 480. 



