1845-1892

Swiss physician and zoologist who in 1877 first observed the penetration of an egg by a sperm cell while studying sea urchins. He showed that the egg nucleus is part of the ovum, and provided evidence supporting the claims of Oskar Hertwig that the nuclei of the cells in an embryo descend from the original egg and sperm pair. Fol was lost at sea during an expedition to study sponges off the coast of Tunisia.