THE MUTATION THEORY 357 
Only one form, O. scintillans, that appeared eight times, is not 
constant as are the other species. When self-fertilized its seeds 
produce always three other forms, O. scintillans, O. oblonga, and 
O. lamarckiana. It differs in this respect from all the other elementary 
species, which mutate not more than once in ten thousand individuals. 
a) 1 Q | 1700 21 ; 
g QO | 3700] 11 
ee leet 
ti | 29 | 3 [1800] 9 | 5 
1 
: | 
o5_| 155 | 20 | g000| 49 {wal 6 
pe sees lena) (OR ed Pes 
i [is | we | 8 oon 60 | 7314 
Fic. 59.—Diagram showing in condensed form the genealogy of the Oenothera 
lamarckiana family and its various mutants during successive years. The numbers 
under each type represent the number of new types observed each year. (From 
Tower.) 
From the seeds of one of the new forms, O. laevifolia, collected 
in the field, plants were reared, some of which were O. lamarckiena and 
others O. laevifolia. They were allowed to grow together, and their 
descendants gave rise to the same forms found in the lamarckiana 
family, described above, namely, O. lata, elliptica, nannella, rubri- 
nervis, and also two new species, O. spatulata and leptocarpa. 
In the Jata family, only female flowers are produced, and, there- 
fore, in order to obtain seeds they were fertilized with pollen from 
other species. Here also appeared some of the new species already 
