Original: He discovered fertilization of sea urchins, he recognized the role of the cell nucleus during inheritance and chromosome reduction during meiosis: in 1876, he found that fertilization includes the penetration of a spermatozoon into an egg cell.
Simplified: He discovered fertilization of sea urchins, he recognized the role of the cell nucleus during inheritance and chromosome reduction during meiosis. In 1876, he found that fertilization includes the penetration of a spermatozoon into an egg cell.