Mutations and Evolution. 
149 
Cruciateness affords the most conspicuous and instructive 
examples of parallel mutations among wild CEnotheras. There are 
indications that the red hypanthium, which is the most conspicuous 
feature of the mutant rubricalyx :, may also be paralleled, though in 
a less degree, by certain wild species. Thus CE. rubescens Bartlett 
(1914b) has buds and hypanthia which are pale red. It would 
appear to agree in this feature with the form, probably hybrid in 
origin, which the writer 1 described from Lancashire under the name 
CE. rubrinervoides. A small-flowered undescribed species, CE. 
Columbiana , from near Washington, is said by Bartlett to have 
“conspicuously red hypanthia.” The writer has pointed out else¬ 
where 2 that the deep red of rubricalyx may become pale red by 
crossing and then back-crossing with a greenish-budded species. 
Thus in (CE. rubricalyx x grandijlora) x grandiflora , if the female 
parent is heterozygous for the red factor, segregation into types with 
red or green hypanthia will take place, but the red will be much paler 
than in the selfed offspring of the female parent plant. In other 
words, the colour is diluted and the red remains permanently pale 
in the selfed offspring of such plants, deep red only being restored 
by a back-cross with rubricalyx. Red or reddish hypanthia in 
plants from all these different sources, indicate its appearance 
through independent variations in different species. 
Parallel Mutations in Drosophila. 
Various features of the Drosophila work will be discussed later. 
In D. melanogaster (ampelophila) certain mutations have occurred 
repeatedly. Thus (Morgan, 1919) white eyes have appeared 
independently three times, vermilion eyes at least six times, rudi¬ 
mentary wings five times, cut wing four times, truncate and notch 
wings each several times, but in the last two cases the change 
involved may not always have been the same. 
In the last five years a number of mutations in six other species 
of Drosophila have been recorded. This includes a new eye-colour 
(scarlet) in D. repleta (Hyde, 1915a), another sex-linked mutation 
(light grey thorax) in the same species (Sturtevant, 1915), a wing 
mutation (jaunty C) in D.confusa (Hyde, 1915b), one in D. tripunctata 
(Metz and Metz, 1915), three mutations (extra bristles, triangle wing 
veins and short wing veins) in D. obscura Fall., and one 
(chocolate eye-colour) in D. similis Will, from Cuba (Metz, 1916b), 
In “ species B,” now known as D. virilis Stt.,a more detailed study 
i Gates, 1914b, 1 Gates, 1914a, 1915f. 
