66 Mutations and Evolution 



and hence fall in class (3). Bateson (1902) first pointed out that 

 in reciprocal crosses made by Darwin between normal and peloric 

 snapdragons, the peloric character behaved as a simple Mendelian 

 recessive, giving 90 non-peloric to 37 peloric in F 2 . Darwin, 

 however, speaks of two of the 90 plants as being " in an intermediate 

 condition between the peloric and normal state." The exact 

 nature of these intermediate plants is not clear. If they 

 correspond to Baur's class (2), then the actual numbers 88 : 2 : 37 

 should be compared with an expectation of 72 : 24 : 32 for the ratio 

 9:3:4. Hence if the behaviour was the same as Baur describes 

 there would be a large excess of normals to account for, and a 

 corresponding defect of " intermediates." 



It is thus obvious that peloria, like doubling, though originating 

 through mutations, behaves differently in different genera. 

 Other mutations in wild and cultivated plants. 



These records are sufficient to show the frequent occurrence 

 of doubles in wild species as parallel mutations, and also of peloria, 

 especially in the Scrophulariaceae. That they are obviously not in 

 any phylogenetic line of descent however, and are more or less 

 incapable of reproducing themselves, detracts somewhat from their 

 evolutionary interest. We may therefore consider some other types 

 of polymorphism which have arisen in wild species or in cultivation. 

 It has been found practically impossible to draw a line between 

 mutations occurring in controlled cultures and the obviously 

 similar changes which are frequently found wild. We therefore 

 feel justified in extending the mutation conception to these wild 

 forms and varieties. 



Linaria alpina, a species of the Alps and Pyrenees, has two 

 varieties, rosea and concolor, whose genetic relationships have been 

 investigated by Miss Saunders (1912). In the typical alpina, which 

 is most common in the Alps, the corolla is blue, with an orange 

 palate, which is partly due to the presence of a viscous orange-yellow 

 fluid in the epidermal cells and the hairs of the beard and partly 

 to the yellowish colour of the cuticle. The var. rosea, which is 

 rare and confined to certain stations, is pink with orange palate 

 and behaves as a simple recessive to the type. Var. concolor is 

 blue without the orange palate, and this is dominant to the type. 

 Each of the varieties therefore differs from the type by one factor, 

 but it is uncertain which was the original form. In L. vulgaris, 

 which is yellow with orange palate, de Vries 1 found on crossing with 

 1 Mutationstheorie, II, p. 152, 



