Surprisingly, little attention has been paid to a part of the activities of Hugo de Vries that was highly valued by himself, namely, the popularization of biology. The appreciable attention paid to De Vries as a rediscoverer of Mendel’s Laws and on account of his mutation theory led to a one-sided image of him as a geneticist and evolutionist. His merits as a plant physiologist have also been mentioned repeatedly, but the fact that he had an expert cognisance of the whole field of botany and was active as a popularizer is hardly known. In particular, foreign scientists often see De Vries only as an experimental researcher and not as the all-round botanist he certainly was.' That Hugo de Vries himself attached much value to popularization is evident from the fact that about half of his many publications are of a popular scientific nature.2 De Vries himself was so much convinced of the importance of botany for Man and human society that he could not help trumpeting this continually. How was it possible that this aspect received so little attention?