Keywords: people indoor Guillaume_Duchenne_de_Boulogne_performing_facial_electrostimulus_experiments Explore The Public Domain Review's 5518 photos on Flickr! Guillaume Duchenne de Boulogne performing facial electrostimulus experiments.jpg Duchenne de Boulogne 1801 - 1875 PD-old Experiments in physiology Facial expressions Adrien Tournachon |