He became a lecturer (1857) and later a professor of botany (1861–1901) at the Eidgenössische Technische Hochschule (Federal Polytechnic School) in Zurich.
[1][2] Cramer's specialty dealt with the physiology, genealogy and growth of plant cells.
He did extensive research in the fields of bacteriology, plant teratology and cryptogamic botany.
[2] In his obituary, Carl Joseph Schröter referred to Cramer as the Altmeister botanischer Forschung ("Doyen of Botanical Research").
[1] He was the author of a number of botanical works, including Pflanzenphysiologische Untersuchungen (4 volumes 1855–58), which he co-wrote with Karl von Nägeli.