MUTATIONS 283 
tral characters. The controversy which arose over these questions 
stimulated investigation to such an extent that the Ginothera literature 
of the past decade would fill many volumes. These investigations have 
proceeded along three definite lines: (1) crossbreeding experiments, 
(2) cytological studies, (3) observations and collections in the field to- 
gether with pedigree cultures. The last of these can only be mentioned. 
See the recent reviews of Davis and Bartlett where further references 
are given. The results of the other two bear directly upon the problem 
of classifying de Vries’ original ‘‘mutations.” 
Concerning the first method of investigating the genetics of Ginothera, 
there have been many crossbreeding experiments in both Europe and 
America. Until recently most of the data derived therefrom have been 
viewed as impossible of interpretation on a Mendelian basis. But since 
1914 certain investigators have come to believe that breeding experi- 
ments with Cinotheras have very little value as a means for exact 
genetical analysis unless complete germination of all viable seeds is 
assured. In that year Renner pointed out that seed sterility in the 
evening primroses may cause apparent nonconformity with Mendelian 
principles. Following up this suggestion with seed germination tests 
and breeding experiments in which all viable seeds were germinated, 
Davis came to the conclusion ‘‘that large proportions of Ginothera seeds 
sprout in the earth only after many weeks or even months and that this 
habit of delayed germination must have given in many of the cultures 
described in the Génothera literature hardly more than glimpses of the 
genetical possibilities. We cannot feel certain that the records of any 
cultures of Ginothera so far reported are complete for their possible 
progeny, and consequently the ratios of classes described in breeding 
experiments and the percentages of ‘mutants’ calculated cannot be ac- 
cepted as final in exact genetical work. We are not in a position even 
to guess what may be the change of front when exact data become avail- 
able. . . . Consequently we have at present in the Gnotheras no 
standard material of genetic purity with which forms under suspicion 
may be confidently mated to determine by crossbreeding the uniformity 
of their viable gametes. Until such material is discovered we shall be 
working largely in the dark in our attempts to analyze the genotypic 
constitution of Gnotheras.’”’ The same author, is inclined to interpret 
data from his most recent Ginothera breeding experiment (biennis and 
franciscana) as giving “positive evidence of a segregation of factors in the 
F, generation of a character to be expected in Medelian inheritance.” 
This inference is the more noteworthy inasmuch as in the past this author 
has not committed himself positively to a Mendelian interpretation of 
any particular data on the @notheras. That certain characters in this 
group are conditioned by specific genetic factors, seems to be generally 
x it,is high] b that th i 
accepted. For en a qu pro) bable at the deeply pigmented 
