strasburger was a founder of the famous "lehrbuch der botanik für hochschulen" ("textbook of botany"), which first appeared in 1894. he was the first to provide an accurate description of the embryonic sac in gymnosperms (such as conifers) and angiosperms (flowering plants), along with demonstrating double-fertilization in angiosperms. he came up with one of the modern laws of plant cytology: "new cell nuclei can only arise from the division of other nuclei", and originated the terms cytoplasm and nucleoplasm.