I have to-day the great honour of delivering an address before the Royal Society, so long renowned as a center of natural science; but I do so with a certain hesitation, being aware that I am not sufficiently master of the English language, and have had but little time for preparation. In consideration of this, I shall avoid entering too much into theoretical discussion: I wish rather to lay stress upon the demonstration of the results of my experiments upon the Influence of Environment on Plants . The problem of the relations of the organism to its surroundings is very old, but it has only recently become an object of active research. In all branches of biology, as well as in the different fields of history, educational science, and so forth, we meet this fundamental problem and also the most conflicting views on it, some of which suffer from exaggeration of the influence of environment, others from its under-estimation.