This article is the full text of the lecture given by Professor K. von Frisch at the opening of the XXII International Beekeeping Congress in Munich on 3rd August 1969, translated from German by Dr. G. Kolisko. It is a first-hand account of some of the discoveries resulting from work done or initiated by Professor von Frisch in Munich, where he was in charge of the Zoological Institute of the University from 1925 to 1958.Those who heard the lecture felt especially privileged to do so, and this publication in English will enable a much wider circle of beekeepers to enjoy the author's clear and intimate exposition. The references on page 152 provide suggestions for further reading on some of the subjects discussed in the lecture.