This edition presents the first complete English translation of N.N. Ladygina-Kohts" journal chronicling her pioneering work with the chimpanzee, Joni. The journal entries describe and compare the instincts, emotions, play, and habits of her son Rudy and Joni as each develops. First published in Moscow in 1935 as a memoir in the Darwin Museum Series, this edition has 120 photographs, 46 drawings and an introduction by Allen and Beatrix Gardner of the Center for Advanced Study at the University of Nevada, as well as a Foreword and an Afterword by Lisa A. Parr, Signe Preuschoft, and Frans B. M. de Waal of the Living Links Center at Emory University.