wild plants only those could be expected to reward the investigator
which were of easy cultivation. For this reason I have limited myself to
the trial of wild plants of Holland, and have had the good fortune to
find among them at least one species in a state of mutability. It was
not really a native plant, but one that had been introduced from America
and belongs to an American genus. I refer to the great evening-primrose
or the evening-primrose of Lamarck. A strain of this beautiful species
is growing in an abandoned field in the vicinity of Hilversum, at a
short distance from Amsterdam. Here it has escaped from a park and
multiplied. In doing so it has produced and is still producing quite a
number of new types, some of which may be considered as retrograde
varieties, while others evidently are of the nature of progressive
elementary species.

This interesting plant has afforded me the means of observing directly
how new species originate, and of studying the laws of these changes. My
researches have followed a double line of inquiry. On one side, I have
limited [28] myself to direct field observations, and to tests of seed,
collected from the wild plants in their native locality. Obviously the
mutations are decided within the seed, and the culture of young plants
from them had no other aim than that of ascertaining what had occurred
in the field. And then the many chances of destruction that threaten
young plants in a wild state, could be avoided in the garden, where
environmental factors can be controlled.

My second line of inquiry was an experimental repetition of the
phenomena which were only partly discerned at the native locality. It
was not my aim to intrude into the process, nor to try to bring out new
features. My only object was to submit to the precepts just given
concerning pure treatment, individual seed gathering, exclusion of