field-observations

Updated: May 5, 2025

In testing this theory by field-observations and culture-experiments, the defenders of the Nagelian principle could easily produce evidence upon the first point. The change of lowland-plants into alpine varieties can be brought about in numerous cases, and corresponding changes under the influence of soil, or climate, or life-conditions are on record for the most various characters and qualities.

Hugo de Vries - Species and Varieties, Their Origin by Mutation

Intermediate forms are very rare, perhaps wholly wanting, though in swamps the terrestrial plants may often vary widely in the direction of the floating type. That both types sport into each other has long been recognized in field-observations, and has been the ground for the specific name of amphibium, though in this respect herbarium material seems usually to be scant.

Hugo de Vries - Species and Varieties, Their Origin by Mutation

A persistent study of the physiologic factors of this evolution is the chief condition of success. To this study field-observations may contribute as well as direct experiments, microscopical investigations as well as extended pedigree-cultures. The cooperation of many workers is required to cover the field.

Hugo de Vries - Species and Varieties, Their Origin by Mutation

But whether, besides this, similar strains are produced anew by the old lamarckiana group, it is impossible to decide on the sole ground of these field-observations. The same holds good with the other novelties.

Hugo de Vries - Species and Varieties, Their Origin by Mutation

Was there some hidden tendency to mutation, which, ordinarily weak, was strengthened in my cultures by some unknown influence? Was the observed mutation to be explained by a common cause with the other cases recorded by field-observations? To answer this question I had only to continue my experiment, excluding the mutated individuals from any intercrossing with their brethren.

Hugo de Vries - Species and Varieties, Their Origin by Mutation