172 BOTANICAL GAZETTE [MARCH 
the least relation to their environments. Even the preference for 
an annual or a biennial behavior, which might seem to be a direct 
adaptation, does not exhibit any reference to the actual life condi- 
tions. The conception of natural selection and of the accumu- 
lation of small variations on account of their utility cannot explain 
the specific and generic differences in this group. 
Therefore it seems unavoidable to assume that specific differ- 
entiation in the genus Oenothera has been produced and is still 
being produced by small steps, each of which evolved a character 
at once to its full development, without any reference to the struggle 
for life. That, besides this process, from time to time new com- 
binations of characters by means of crosses may have given rise 
to constant hybrid strains, which we have as yet no means of 
distinguishing from pure species, cannot of course be doubted. 
Now, Oenothera Lamarckiana, O. biennis, and some allied forms 
are seen to be still in a condition of making, from time to time, 
such small steps. They are doing this in their natural habitats 
as well as in experimental cultures, and the variations produced 
show no relation to the external conditions of their environment 
or to the method of their culture. On this ground, the claim seems 
justified that the mutations, directly observed in the primroses, 
are similar to those which have produced in nature the specific 
differences and the differentiating characters in this group. If 
this is conceded, it follows that the analogous processes in other 
genera, and even in the origin of the larger systematic groups, must 
be viewed in the same way. This claim, however, has not escaped 
serious objections. 
e main line of these attacks is based upon the vague and 
double assumption that O. Lamarckiana might be a hybrid, and 
that its hybrid origin might account for its:present mutability. 
These two assumptions are evidently independent of one another 
and would have to be proven separately. So far as I know, no 
attempts have been made as yet to prove the second assumption, 
and no hybrid races have been produced which, from this cause, give 
rise to phenomena exactly duplicating the mutations of the prim- 
roses. And it is evident that so long as such an analogy is only 
an ardent wish of the critics, the question whether the mutating 
