REVIEWS. 
59 
REVIEWS. 
Species and Varieties: Their Origin by Mutation,* 
IV. 
New Species of Oenothera.- —The experiments with pelories and double 
flowers demonstrated how varieties originate. How species originate can 
be learned only by watching the process—by direct observation. Further 
only the elementary species can be observed to originate, for the syste¬ 
matic species “ are only artificial groups of lower unities (and) can 
never become the subject of successful experimental inquiry.” A species 
must be chosen which is now in a mutating period, and historical evi¬ 
dence leads us to believe that a species in such a condition may be found. 
After patient observation the evening primrose of Lamarck ( Oenothera 
Lamarckiana ) was discovered to be in a state of mutation, and plants 
were transferred to the experimental garden, and seeds sown for the 
purpose of observation. “ Over a dozen new types never previously ob¬ 
served or described ” were seen to originate ah once—not by slow degrees 
—from the seeds of this plant. There were 5 groups of these types—1, 
ordinary varieties, e. g., laevifolia, brevis tylis, and nanella; 2 and 3, 
progressive elementary species, (2) strong, e. g., gigas, (3) weak, rubri- 
nervis, albida, oblonga; 4, inconstant forms, lata, scintillans, elliptica; 
5, forms organically incomplete. The varieties—especially nanella and 
the second and third types—are absolutely constant from seed, showing no 
tendency to revert to the Lamarckiana type. Lata bears no pollen. In 
scintillans only a fraction of the seed comes true, the rest are like Lamarck¬ 
iana, and its progeny are largely mutable. Elliptica also repeats its type 
only in a small per cent, of its seed. 
Laws of Mutability. —Thus the fact of mutation in plants is established, 
and as the result of extensive and painstaking pedigree-cultures the fol¬ 
lowing laws of mutability for the evening-primroses are formulated. 
1. “New elementary species appear suddenly, without intermediate 
steps.” 
2. “ New forms spring laterally from the main stem.” One species is 
not slowly converted into another as has sometimes been erroneously 
held, but new species are derived from antecedent species which may still 
persist. Lamarckiana is in no danger of dying out from the act of mu¬ 
tating. Also the new species originating from an old one are not re¬ 
stricted to one type, but several may spring at once from one parent. 
3. “ New elementary species attain their full constancy at once.” Con¬ 
stancy is not the result of selection. 
4. “ Some of the new strains are evidently elementary species, while 
others are to be considered as varieties.” 
5. “ The same new species are produced in a large number of individu- 
* Species and Varieties: Their Origin by Mutation. Hugo de Vries, 
edited by D. T. MacDougal. Chicago: The Open Court Pub. Co. 1905. 
