SEE EGE. of ter 
VOLUME LVII NUMBER 5 
THE 
DOTANICAL ©7120 
MAY. ror4 
THE PROBABLE ORIGIN OF OENOTHERA 
LAMARCKIANA SER. 
Huco DeE VRIES 
(WITH PLATES XVII-XIX) 
In a series of most interesting articles, B. M. Davis has recently 
tried to prove that mutability might be a result of previous crosses. 
This view was first proposed by BATESON and SAUNDERS, and 
applies especially to the phenomena which Oenothera Lamarckiana 
shows when seeds from the pure strain, and even from pure lines 
within this strain, are sown, as in the experiments I conducted in 
my experimental garden. Davis expected to be able to offer the 
desired proof by showing that O. Lamarckiana might be duplicated 
by crossing two other species of the same group. Up to this time, 
as a matter of fact, he has not succeeded in producing any form 
which comes sufficiently near O. Lamarckiana to be compared with 
it* But if he had succeeded in doing so, evidently it would not 
have been a proof for his assertion, unless his hybrid should show 
the same degree of mutability as does O. Lamarckiana, since we 
have as yet no means of judging from the morphological characters 
of a given plant whether its hereditary characters are in a stable 
or in an unstable condition. - 
In starting his experiments to produce a duplication of 
LAMARCK’s evening primrose, Davis was unfortunate in the choice 
of the species for his combination. He chose O. biennis L. and a 
*For a successful duplication of an elementary species by means of crossing, 
See Oenothera biennis XO. cruciata Nutt. in Gruppenweise Artbildung, p. 311. 
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