a few were triennial; best of all, it showed what can hardly be otherwise described than as new species in the making.
"It is possible that the prolific;multiplication in a new environment may have had something to do with the awakening of the impulsive mutability.
"In 1887, a year after his discovery of the potato-field, De Vries found two well-defined new forms—a short-styled O. brevistylis and a beautiful smooth-leaved O. lævifolia—distinguishable from the parent in many details. He hailed these as two new ' elementary species,' and he applied one of the crucial tests of specific or sub-specific rank: Did they breed true? He found that it was so; from their self-fertilised seeds similar forms arose. Neither of the two new forms was represented in the herbaria at Leyden, Paris, or Kew; neither had been described in the literature of Onagraceæ, They seemed to be distinctly new. It is interesting to note that in 1887 there were few examples of these two new elementary species, and that each occurred on a single plot on the field. The impression conveyed was that each had arisen—by a sudden mutation—from the seed of an individual parent.
"The next chapter in the famous investigation began with a transference of samples of the new forms and the parent stock—partly as plants
